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'The Science and Practice of 

Cheese-Making 



A Treatise on the Manufacture of Amer 
ican Cheddar Cheese and other varieties 

intended as a text-book for the use of dairy teachers and 

students in classroom and workroom ; prepared also 

as a handbook and work of reference for the 

daily use of practical cheese-makers 

in cheese-factory operations 



By 
Lucius L. Van Slyke, Ph.D. 

Chemist of the New York Agricultural 
Experiment Station 

and 

Charles A. Publow, A.B., M.D., CM. 

Associate Professor of Dairy Industry in the New York State 
College of Agriculture at Cornell University 



Illustrated 



New York 

Orange Judd Company 
1909 



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LIBRARY of CONGRESS 
Two CoDies Recerved 

FEB 3 1909 

Copyriicnt entry 

^ASS O^ XX& No, 

COPY 3. 



t 

Ha. 



Copyright, 1909 

Orange Judd Company 

New York 



All Rights Reserved, 



[Printed in U. vS. A.] 



PREFACE 

This book has been prepared to supply a need 
definitely expressed by dairy teachers, dairy stu- 
dents and cheese-makers. To meet the require- 
ments of to-day, a book on cheese-making must be 
something more than a mere description, in a 
recipe-like form, of certain operations to be per- 
formed ; it must also make prominent the reasons 
for each step- in every operation and present as 
clearly as possible the facts and principles under- 
lying the methods ; in other words, it must present 
the science as well as the practice of cheese-making. 

Knowledge of cheese-making, as of any art, is 
two-sided, practical and scientific. Practical knowl- 
edge tells us zvhat to do; scientific knowledge gives 
us the reasons for zvhat is done. Practice consists in 
doing things ; science, in knozving things. Knowledge, 
to be complete, must be both practical and scientific ; 
we must know not only zvhat particular things to do 
but zvhy we do them. Just in proportion as the prac- 
tical and the scientific sides of knowledge advance 
together, does the practice become more nearly per- 
fect. The more one knows, the more and better can 
one do. 

The practice of cheese-making embraces a systematic 
series of mechanical operations, which have been 
gradually developed by experience and observation. 
In its widest application, it includes (i) the produc- 
tion and care of milk; (2) the conversion of milk 
into cheese; and (3) the care of the manufactured 
product until it is ready to be used as food. 



VI PREFACE 

The science of cheese-making embraces a collection 
of the underlying facts and principles relating to 
the practice, arranged in systematic form so as 
to show their relations. For example, it includes, 
among other lines: (i) A knowledge of the con- 
stituents of milk — what each has to do in the mak- 
ing of cheese and how each is related to the yield, 
composition and quality of the product; (2) the 
changes which each constituent of milk may under- 
go and the effect of such changes upon the yield, 
composition and quality of cheese; (3) the action of 
micro-organisms upon the constituents of milk and 
of cheese; (4) the effect of unorganized ferments 
upon milk and cheese; (5) the effect of temperature, 
humidity and other conditions upon the chemical 
changes that take place during the operations of 
cheese-ripening. 

While cheese has been made for thousands of 
years, the growth of accurate, systematic knowledge 
regarding its inner details has been extremely slow ; 
but within the past twenty years there has been an 
era of unprecedented activity in the investigation of 
the chemical, biological and other problems con- 
nected with milk and cheese. As the result of the 
application of new knowledge thus gained, the prac- 
tice of cheese-making has undergone marked im- 
provements. The problems that are peculiar to the 
manufacture of American cheddar cheese have been 
studied extensively in the United States and Can- 
ada, mainly under government direction in some 
form, and more especially at agricultural experi- 
ment stations. Two institutions have been promi- 
nent for the extent and thoroughness of their 



PREFACE Vll 

investigations and for the far-reaching influence of 
the results of their work — the agricultural experi- 
ment stations of the states of Wisconsin and 
of New York (Geneva). The results of these and of 
other useful investigations are not now easily avail- 
able, being scattered through many reports and 
bulletins, most of which can be found only in large 
libraries. One of the tasks proposed at the outset 
in the preparation of this book was to digest this 
large mass of valuable material and present the 
results in systematic form, thus making it for the 
first time readily available to all dairy students. An 
exhaustive, detailed history of these investigations 
would compel one to present some results and in- 
terpretations which more accurate work has later 
shown to be erroneous. Those for whose use this 
book has been prepared are more interested in 
knowing what the status of our present knowledge 
is than in studying the various details which have 
preceded. The chief aim, therefore, has been to 
digest and summarize the results of investigation 
in such a way as to give what, in the light of our 
present knowledge, we may now regard as the 
probable facts and their proper interpretation. This 
task is a somewhat discouraging one, because new 
facts are being rapidly added to our knowledge 
and, in consequence, what we may now hold as 
true is quite likely to need modification in the near 
future. 

The main portion of this book is devoted to 
Cheddar cheese for the obvious reason that this is 
the kind most extensively made in America. A 
few other kinds of cheese are briefly discussed, so 



Vlll PREFACE 

far as the assigned limits permit. Even in relation 
to Cheddar cheese, the book is not intended as an 
encyclopedia, but an effort has been made to have 
it reasonably complete. 

The language used by the practical cheese-maker 
in describing the operations of cheese-making has 
inevitably expressed his theories or explanations 
of observed facts. Many expressions have persisted 
even after they were known not to be in accordance 
with facts. It has seemed highly desirable that 
such inaccuracies should be corrected and the lan- 
guage made to correspond with our advanced 
knowledge. In addition, there have been many in- 
accurate and loose expressions in common use 
which have come simply from carelessness and lack 
of precision. Such expressions have been carefully- 
revised in the preparation of this book. 

A few words in regard to the general plan of the 
book will not be out of place here. The subject 
matter is divided into five parts. The first part is 
devoted mainly to a description of the operations 
employed in making American cheddar cheese un- 
der normal conditions, including the care of cheese, 
factory construction, equipment, etc. This portion 
of the subject is placed first in order in the book, 
as a matter of convenience, because it is the por- 
tion which will be most commonly referred to in 
connection with practical work. In order to avoid 
overloading the description of methods of cheese- 
making with too many details in the way of ex- 
planations, precautions, etc., many of these points 
are discussed with fullness in later portions of the 
book, appropriate references being given in part 



PREFACE IX 

first. The second part is devoted to a study of the 
various defects that may occur in cheese as the 
result of abnormal conditions in the process of 
cheese-making. The third part, which comprises 
more than one-half of the book, is devoted to the 
science of cheese-making. This is the first attempt 
to treat the subject in a comprehensive, systematic 
manner. It is realized that not all of the chapters 
will appeal equally to those who use the book. For 
a satisfactory understanding of Chapter XXIV, 
some knowledge of chemistry is required. The 
fourth part of the book contains a description of 
methods of making some other varieties of cheese 
than American cheddar. In the fifth and last part 
are given a description of the tests used in cheese- 
making, an indexed bibliography of the subject, and 
other matter of a miscellaneous character. 

Each illustration has been carefully selected with 
reference to giving supplementary, helpful, and 
specific information. The use of illustrations as a 
means of padding the book, or as a source of en- 
tertainment without reference to the subject-mat- 
ter, has been carefully avoided. 

In using this book, teachers will adapt it to the 
special conditions under which they work or to 
the special purpose they have in mind. For ex- 
ample, the amount and kind of matter studied will 
differ in the case of short-course and of long-course 
students. Material will be found for those most ad- 
vanced, as well as for beginners. Good judgment 
will need to be exercised in respect to the combi- 
nation of the different parts, but assistance in this 
respect is given by means of specific references. It 



X PREFACE 

is not expected that any book, however complete 
and clear, .will enable one to make cheddar cheese 
successfully without the help of a competent 
teacher. 

It is appreciated that, in the preparation of a 
work on new lines, the results are inevitably far 
from perfect. Those who have occasion to use this 
book will confer a favor if they will be free to call 
the attention of the authors to any defects which 
they find, whether in the line of omissions, incom- 
plete treatment or inaccuracy of statement. 

As to the respective shares of the work for which 
the authors are severally responsible, Chapters II, 
III, IV, V and XXVII represent combined work; 
Mr. Van Slyke has written, for the most part, 
Chapters I, VI and VIII; Mr. Publow, except for 
some minor changes and additions, has written 
Chapters VII and IX to XIII inclusive ; Mr. Van 
Slyke has written Chapters XIV to XXVI inclu- 
sive, and also Chapters XXVIII to XXX. 

We desire here to express our appreciation of 
valuable assistance received in various ways from 
the following persons : Mr. G. G. Publow, King- 
ston, Ontario, Canada, Chief Dairy Instructor in 
cheese-making; Mr. George A. Smith, Geneva, 
N. Y., Dairy Expert at the New York Agricultural 
Experiment Station ; Mr. Alfred W. Bosworth, 
Geneva, N. Y., Associate Chemist at the New York 
Agricultural Experiment Station ; and Dr. Donald 
D. Van Slyke, New York City, Assistant Chemist 
at the Rockefeller Institute for Medical Research. 

September, 1908. 



CONTENTS 



PART I. 

Page 

The Manufacture of American Cheddar Cheese. 

I. 
The Care of Milk for Cheese-Making .... 3 

II. 

Preliminary Steps in Making Cheddar Cheese . . 15 

III. 
Operations from Cutting Curd to Salting .... 25 

IV. 
Operations from Salting Curd to Removal from Press . 37 

V. 
Moisture and Acidity in Curd and Cheese: Conditions, 

Effects and Control "+5 

VI. 
Modifications of Cheddar Process and Miscellaneous 

Subjects ^^ 

VII. 
Care, Shipment and Sale of Cheese .... 71 

VIII. 
Commercial Qualities of Cheddar Cheese and Methods of 

Judging ^ 

IX. 

07 
Cheese-Factory Construction ^' 

X. 

Cheese-Factory Equipment ^^ 

xi 



Xll TABLE OF CONTENTS 

Page 

PART II. 

Defects of American Cheddar Cheese: Causes, 
Remedies and Means of Prevention. 

XI. 
Defects in Flavor . . . . . . . .115 

XII 
Defects in Body and in Texture ..... 121 

XIII. 
Defects in Color and in Finish 129 

PART III. 

The Science of Cheese-Making : The Chemical, Bio- 
logical and Other Relations of Milk and Cheese. 

XIV. 
The Constituents of Milk 139 

XV. 

Conditions Affecting Proportions of Constituents in Milk . 155 

XVI. 
Functions of Milk Constituents in Cheese-Making . . 177 

XVII. 
Milk Constituents and Yield of Cheese . . . 186 

XVIII. 
Methods of Calculating Yield of Cheese . . . .211 

XIX. 

Milk Constituents in Relation to Composition of Cheese . 231 

XX. 

The Composition of Cheese in Relation to Quality . . 243 

XXI. 

Methods of Paying for Milk for Cheese- Making . . 2S3 



TABLE OF CONTENTS Xlll 

Page 

XXII. 
The Relations of Micro-Organisms and Enzyms to Cheese- 
Making ......... 285 

XXIII. 
The Ripening of Cheese 313 

XXIV. 
Chemical Changes in Cheese-Ripening .... 327 

XXV. 
Causes of Chemical Changes in Cheese- Ripening . . 354 

XXVI. 

Commercial Relations of Cheese-Ripening , . . 379 

PART IV. 

XXVII. 

Methods of Making Different Varieties of Cheese . . 398 

PART V. 

Methods of Testing, Factory Organization 
and Literature. 

XXVIII. 
Methods of Testing Used in Cheese-Making . . . 423 

XXIX. 
Cheese-Factory Organization and Management . , 447 

XXX. 
The Literature of Cheese-Making .... 454 



ILLUSTRATIONS 



Page 

American Cheddar Cheese Frontispiece 

M'icroscopic Appearance of Clean Milk 4 

Microscopic Appearance of Unclean Milk .... 4 

Sanitary Milking-Pails 10 

Aerator and Cooler 11 

Dipper for Use in Cheese-Making » 20 

McPherson Hand-Agitator for Stirring Curd ... 28 

Double-Toothed Curd-Rake 29 

Effect of Excessive Moisture in Soaked-Curd Cheese . 58 

Abnormal Texture of Soaked-Curd Cheese .... 59 

Weighing, Paraffining and Boxing Cheese .... 74 

Apparatus for Paraffining Cheese 75 

Appearance of Perfect Cheese-Box 78 

Close-Textured Cheese 84 

Loose-Textured Cheese 84 

Texture of Sweet -Curd Cheese 84 

Texture Caused by Gas 85 

Mechanical-Holes in Cheese 85 

Swiss-Holes 86 

Design for Septic Tanks 101 

Cold-Air Circulation in Curing-Room 102 

Plan Showing Arrangement of Cheese-Factory Equip- 
ment 103 

Plan for Cheese-Factory . 105 

Steel Cheese-Vat 107 

Barnard's Curd-Cutter 108 

Gosselin Curd-Mill 108 

Continuous-Pressure Gang-Press 109 

Eraser and Wilson Hoops 110 

Apparatus for Showing Humidity in Air . . . . Ill 

Fish-Eye Texture in Yeasty Cheese 126 

Seamy Color and Lack of Pressure 131 

Brine-Soluble Protein of Cheese Drawn out in Strings . 148 

Diagram Showing Composition of Milk 195 

Distribution of Milk-Constituents in Cheese and Whey 196 

Yield and Composition of Cheese from Different Milks 206 
Yield and Composition of Cheese from Milks of Different 

Breeds 208 

XV 



XVI ILLUSTRATIONS 

Page 

Effect of Skimming Milk on Composition and Yield of 

Cheese 235 

Ball-Shaped Bacteria 287 

Chains of Ball-Shaped Bacteria . . . . . . .287 

Rod-Shaped Bacteria . . ^ 288 

Bacteria with Swimming Hairs 288 

Effect of Temperature on Bacteria 290 

Lactic Acid Bacteria , . . .292 

Close-Textured Cheese Ripened at Different Tempera- 
tures 324 

Sweet -Curd Cheese Ripened at Different Temperatures 325 
Devices for Keeping Records of Temperature . . 384-385 

Appearance of Frozen Cheddar Cheese 390 

Edam Press-Mold and Cover 412 

Cross-Section of Edam Press-Mold and Cover . . .413 

Edam Salting-Mold in Cross-Section 413 

Edam Salting-Mold, Inside and Outside Appearance . 414 
Parts of Gouda Mold Shown Separately . . . .418 
Parts of Gouda Mold United 418 



Part I 

The Manufacture of American 
Cheddar Cheese 

Detail «? of cheese-making operations 
from care of milk to sale of cheese. 

Commercial qualities and methods 
of judging. 

Cheese - factory construction and 
equipment. 



The Science and Practice of 
Cheese-Making 



CHAPTER I 

The Care of Milk for Cheese-Making 

One of the fundamental requisites of successful 
cheese-making is clean milk. The cheese-making 
process begins in reality on the premises of the milk 
producer; and, of all the details of the process, the 
one that is, and has always been, productive of most 
trouble is the improper handling of milk by patrons. 
There has usually been complete absence of any ade- 
quate method in caring for milk. The occasional 
skimming or watering of milk always calls forth the 
severest condemnation, and properly ; but actual losses 
caused dairymen in this way are insignificant in com- 
parison with the losses caused by carelessness and 
neglect in properly caring for milk. It is to be hoped 
that the time may come when deliberate carelessness 
and indifference in the production and care of milk 
will be regarded as little short of criminal. The value, 
of milk in cheese-making depends, in no small degree, 
on the care it receives from the time it is drawn from 
the udder until it is delivered at the factory. The 
quality of milk in respect to its cleanliness determines, 
to a great extent, the quality of cheese that can be 
made from it. 



4 SCIENCE AND PRACTICE OF CHEESE-MAKING 

When milk is not properly cared for by patrons, it 
may acquire undesirable characteristics, which injure 
its usefulness in cheese-making, such, for example, as 
hig-h acidity, acquiring offensive odors and tastes, 
forming gases, etc. 

The causes of these defects will be briefly con- 
sidered under four headings : ( i ) Bacterial infec- 
tion, (2) absorption of flavors, (3) food eaten, (4) 
physiological or disease processes in cows. 

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FIG. 1 FIG. 2 

Appearance of clean milk under Appearance of unclean milk under the 

the microscope. Only fat-globules microscope. The li^ht, round bodies are 
are seen. fat-globules ; the dark masses are groups 

of bacteria and cellular matter. 



SOURCES OF BACTERIAL INFECTION 

Milk, when drawn with careful precautions from 
the udder of a cow, contains comparatively few 
bacteria; but milk obtained and handled under ordi- 
nary conditions is found to contain large numbers, 
often several hundred thousand, in one cubic centi- 
meter (somewhat less than one-quarter of an ordinary 
teaspoonful). The more dirt there is in milk, the 



CARE OF MILK FOR CHEESE-MAKING 5 

more bacteria there will be. Bacteria and dirt always 
g-o together in dairy matters. The relations of bac- 
teria to milk are considered in greater detail in 
Chapter XXII, p. 285. 

The most common sources of bacterial infection are 
the following: (i) Unclean or unhealthy condition 
of cows; (2) unclean condition of stables or places of 
milking; (3) unclean condition of persons milking 
cows; (4) unclean condition of utensils used; (5) 
keeping milk in unclean surroundings, and especially 
at temperatures above 60° F. after milking. 

Unclean condition of cows. — The hair on cows 
favors the accumulation of dirt and dust. The con- 
dition is worse in proportion as cows are not regu- 
larly and thoroughly cleaned. Dust particles and 
hairs, laden with bacteria, are in position to drop into 
the milk-pail. While the hairs and coarse chunks of 
dirt may be removed from milk by straining, the 
bacteria are, in large part, washed off intO' the milk 
and cannot be removed by any ordinary process of 
straining. 

Unclean condition of stable. — A dirty condition 
of the floors, walls and ceilings of a stable all tend to 
contaminate milk. Any condition in the stable that 
affords a supply of floating dust at the time of milking 
furnishes additional bacteria for milk 

Unclean condition of milker. — The hands and 
clothing of a milker may easily be loaded with bacteria 
and thus become a source of infection. Particularly 
objectionable is the filthy practice of moistening the 
hands with milk when milking. 

Unclean utensils, especially the milk-pails, strain- 
ers and milk-cans. The cracks and joints of all 



6 SCIENCE AND PRACTICE OF CHEESE-MAKING 

utensils made of tin, unless great care in cleaning is 
used, contain dirt that holds large numbers of bacteria. 
Rust and imperfect soldering of joints furnish places 
for dirt to get out of easy reach. Without prompt 
and extreme care, strainers easily become filthy and 
are then simply breeding places for bacteria. When 
milk cans are used for carrying back whey to the farm 
from the cheese-factory, the cans often are not cleaned 
promptly, and, when finally attended to, are not treated 
with proper thoroughness. Through the medium of 
a dirty whey-vat, filth, as well as disease, germs 
may be distributed throughout the whole neighbor- 
hood. Even epidemics of typhoid fever have been 
traced to this source of infection; certain diseases 
have been similarly distributed among farm ani- 
mals, as, for example, tuberculosis^ in calves and 
hogs. 

Unclean surroundings after milking. — Milk, even 
when drawn under the cleanest possible conditions, 
very easily becomes contaminated by being kept, even 
for a short time, in any place that is not clean. 

Keeping milk cool. — At temperatures above 60° 
F., milk more rapidly undergoes fermentation changes 
than at lower temperatures (p. 290). 

ABSORPTION OF FLAVORS 

. Milk, particularly when warm, possesses remarkable 
ability to absorb and retain odors present in the sur- 
rounding air. The most common sources of such 
odors are the manure in unclean stables and any 
strong-smelling food present In the stable during milk- 
ing-time. Among the most common conditions under 



CARE OF MILK FOR CHEESE-MAKING 7 

which undesirable flavors are absorbed are the keep- 
ing of milk in or near cellars, silos, stables, pig-pens, or 
any place where strong-smelling substances of any 
kind are present. 

FLAVORS FROM FOOD EATEN 

Certain foods that have strong taste and odor Im- 
part to milk their characteristic flavors wiien eaten 
within a few hours before milking. Most common 
among these are onions, garlic, rape, turnips, leeks, 
cabbages, ragweed and decayed ensilage. Experi- 
ments have shown that with most of these the effects 
are largely, if not entirely, avoided when milk is not 
drawn for 8 to 12 hours after such food is eaten, 
provided an abnormal amount has not been taken. 
Similar results, but in milder form, may come from 
the feeding of excessive quantities of such materials 
as swill, brewers' grains and distillery slops. It is 
a safe rule, in the case of milk to be used for cheese, 
not to use at all such foods as are in danger of taint- 
ing milk, such as turnips, cabbages, rape, etc., and to 
keep cows where they cannot get at anything that 
may endanger the quality of the milk for cheese- 
making. Some green fodders, like second-growth 
clover, rye, etc., have been found to produce gassy 
and tainted milk and cheese. Such a condition is 
more likely due to bacteria on these foods than to 
any peculiar property in the foods themselves. 

There is one marked point of difference between 
bad flavors of bacterial origin and those coming from 
absorbed flavors and strong-smelling food. The 
latter manifest their presence in the milk clearly 



8 SCIENCE AND PRACTICE OF CHEESE-MAKING 

when the milk is dehvered at the factory and may 
be largely removed by proper aeration and care 
in the cheese-making- operations ; but those of 
bacterial origin do not usually reveal their presence 
until the cheese-making process is well along, or not 
even until the cheese has been made and acquired 
some age. 

PHYSIOLOGICAL OR DISEASE PROCESSES 

IN COWS 

It is well known that if a cow is abnormally 
heated or excited just before milking, tainted milk 
and cheese may result. Such a condition may be 
brought about by dogging cows or any form of 
ill treatment. Many diseases directly affect cow's 
milk and render it unfit for use in making cheese. 

HOW TO OBTAIN CLEAN MILK 

We have seen that the one chief source of bacteria 
is dirt. Hence, the one thing needful to prevent 
bacteria getting into milk is extreme cleanliness at 
every point of contact with the milk. The following 
suggestions are given to indicate what is meant by 
cleanliness in connection with milking and caring for 
milk. 

Covers should be clean and healthy. — Too much 
pains cannot be taken to keep cows clean. In ad- 
dition to regular currying and brushing all over, the 
udder and adjacent portions of the body should be 
carefully brushed before milking and also wiped with 
a damp, clean cloth. The udder should also be wiped 



CARE OF MILK FOR CHEESE-MAKING 9 

after milking. The best way to clean the parts is by 
using warm water and a cloth. The cleaning is made 
easier by clipping the hair close to the abdomen, udder 
and flanks. Dry-brushing of the udder before milking 
should not be practiced, as it makes conditions worse 
by stirring up dust which settles into the milk-pail. 

The stable. — Every condition about the stable 
should be regulated with reference to absence of dirt, 
an abundant supply of pure air, and a direct exposure 
to sunlight. The floors should be tight and of a ma- 
terial not readily absorbing liquids. An abundance of 
clean bedding should be used, and the manure should 
be removed more frequently than once a day, and, in 
any case, not immediately before milking. The walls 
and ceiling should be swept often enough to prevent 
the accumulation of dust, but never just before milk- 
ing-time. Once a year, at least, it is wise to clean 
the entire stable with extreme care and then go over 
the whole with a generous coat of whitewash. At 
such a time the stable should be thoroughly disin- 
fected if there has been any contagious disease in 
the stable. The surroundings outside of the stable 
should be kept in a clean condition, so as not to in- 
terfere with the supply of pure air. Where water 
pressure can be had, as in case of a windmill, storage 
tank, etc.j hose should be used in cleaning. 

Milking. — The milker should wash his hands care- 
fully before milking and have them perfectly dry while 
milking. It is also desirable to have a special coat or 
jacket for milking, made of some material that will 
not catch or hold dust easily. Only small-top milking- 
pails should be used. (Fig. 3.) 



10 SCIENCE AND PRACTICE OF CHEESE-MAKING 

Cleaning dairy utensils. — All utensils that come 
in contact with the milk, such as milk-pails, milk-cans, 
aerators, etc., should be made of metal, preferably of 
pressed tin, with smooth, well-flushed joints and per- 
fect seams. They should be kept entirely free from 
rust. Such vessels should never he allowed to dry 
when dirty, as dried particles of milk are particularly 
difficult to remove. In cleaning dairy utensils, rinse 
them first with cold or lukewarm water ; and then 
scrub with a brush, using- water containing some good 
washing-powder that will remove grease. Then scald 




FIG. 3 — DIFFERENT STYLES OF SANITARY MILKING-PAILS 



with boiling water and complete the cleansing, if pos- 
sible, by exposing to a jet of live steam for three to 
five minutes. Never dry with a cloth, but, when 
practicable, expose the utensils finally to direct sun- 
light for a few hours. Dust and flies should be pre- 
vented from entering the cans after washing. 
Strainers should be washed immediately after 
using, cleaning first in tepid water, following with 
hot water and soap or washing-powder and finally 
with hot water and then with steaming or boiling. 

Treatment of milk after milking. — As soon as 
each cow is milked, the milk should be removed from 



CARE OF MILK FOR CHEESE-MAKING 



II 



the stable to some room free from all odors and 
with cleanly surroundings. The milk should be at 
once strained through a brass-wire strainer, having 
not less than fifty meshes to the inch, and also 
through three or four thicknesses of cheese-cloth. Still 




FIG. 4 

An ideal way of cooling milk. The milk in a thin 
layer runs over a surface made cold l)y running ice- 
water. The same water can be used repeatedly by 
adding ice each time. 




FIG. 5 

The milk contained in 
these long "shot-gun" pails 
or cans,placed in ice-water 
is stirred occasionally to 
insure even cooling. 



more effective results in straining can be secured by 
the use of absorbent cotton, though its expense may 
make its use impracticable under ordinary conditions. 
After straining, cool at once to 60° F., or better to 
50° F., by ice or cold water. (Figs. 4 and 5.) 



12 SCIENCE AND PRACTICE OF CHEESE-MAKING 

Cleanliness and prompt cooling are two of the most 
important factors that enter into the successful manu- 
facture of cheddar cheese. 

Aeration. — In aerating milk, the following condi- 
tions should be carefully observed for the best 
results: (i) Aeration should take place only in a 
pure atmosphere. (2) Aeration should be per- 
formed at body temperature and therefore is best 
done immediately after milking. (3) Aeration should 
precede cooling and not be simultaneous with it. 
(4) Aeration should be carried out over the most 
extensive surface possible and as slowly as possible. 

Feeding-time. — Foods having marked odors 
should be fed only after milking and then at once, and 
none should be left in the stable. Dry fodders, which 
furnish dust, should likewise be fed after milking. 

Diseased milk. — The milk of diseased animals 
should not be used nor that of animals fresh in milk 
before the ninth milking. Colostrum milk (p. 158) 
should never be used for cheese-making. The presence 
of such milk seriously affects the operations of cheese- 
making in the following manner: Soon after cutting, 
the curd becomes softer and will not firm sufficiently 
to make good cheese. 

Contagious diseases. — No person suffering from, 
or recovering from, a contagious disease, nor any per- 
son that has anything to do In caring for such a 
person, should be allowed to have any contact with the 
dairy. 

JUDGING MILK FOR CHEESE-MAKING 

The only solution of the problem of obtaining clean 
milk for cheese-making lies in' the education of the 



CARE OF MILK FOR CHEESE-MAKING I3 

milk producer. It is necessary to do more than dis- 
tribute printed instructions. Personal inspection of 
individual farm premises is also necessary. But it is 
essential, in addition to these methods of education, 
to give some additional specific inducement which will 
impress each patron as nothing else will and lead him 
to recognize not only the general importance of pro- 
ducing clean milk, but the application to him person- 
ally. The most effective means of making a deep 
impression is to give each one an opportunity to see 
how far his milk departs from the recognized standard 
of milk that is clean enough for making good cheese. 
These results can be realized by the introduction of a 
system of judging milk; and if the results of each 
judging can be made to affect the dividends, the pa- 
tron soon realizes how near or how far from the 
proper standard his milk is. 

The following method is suggested as an effective 
one in judging cheese-factory milk: Examine the 
milk for (i) acidity, (p. 426); (2) dirt in suspen- 
sion, (p. 434) ; (3) micro-organisms by the fermen- 
tation test, (p. 434) ; and (4) flavor. Use the fol- 
lowing scale of points for scoring milk: 

When perfect 
Acidity 15 

(Acidity not over 0.18 per cent.) 

Dirt IS 

(No dirt in suspension.) 

Fermentation test 45 

(No signs of abnormal ferments.) 
Flavor 25 

(Entire freedom from abnormal odor and taste.) 

In each milk, the score is diminished in the case of 
each quality if the milk shows any imperfections. This 
system will be found effective in application, if the 



14 SCIENCE AND PRACTICE OF CHEESE-MAKING 

judging is done carefully and the results made known 
to the patrons. If patrons can be persuaded to apply 
the results of such judging to the distribution of divi- 
dends, the work would be more effective, of course. 
For example, a patron's dividend could be marked 
down one cent per lOO pounds of milk for each ten 
points his milk scored below lOO on the above system. 
Of course, this method does not apply to cases in 
which the milk is obviously bad when brought to the 
factory. The only remedy in such cases is to refuse 
the milk altogether. 

This is a matter which should be discussed at the 
annual meeting of patrons, in case of co-operative 
factories, when some definite policy should be adopted 
and intelligently enforced. For a more complete treat- 
ment of the subject of judging and scoring milk, see 
Modern Methods of Testing Milk and Milk Products, 
pp. 182-192 (published by the Orange Judd Co.). 



CHAPTER II 

Preliminary Steps in Making 
Cheddar Cheese 

In entering upon the detailed study of the methods 
of cheese-making we shall present the subject in ac- 
cordance with the following outline of the different 
steps in the various operations that are performed: 

(1) System of keeping records of the operations of 
cheese-making. 

(2) First care of milk at the factory, 

(3) Ripening the milk. 

(4) Adding color. 

(5) Coagulating the milk by rennet. 

(6) Cutting the curd. 

(7) Heating the curd. 

(8) Removing the whey from the curd. 

(9) Cheddaring the curd. 

(10) Milling the curd. 

(11) Salting and pressing curd and dressing cheese. 

(12) Care, shipment and sale of cheese. 

In describing the details of the methods of making 
American cheddar cheese, we shall limit our treatment 
largely to normal conditions^ reserving for separate 
treatment abnormal conditions (p. 112). An 
effort is made not to overload the description with 
unnecessary details. The explanation of many de- 
tails is given in other chapters, to which reference 
will be made as needed, instead of incorporating 
them with the description of the cheese-making 
operations. 

15 



l6 SCIENCE AND PRACTICE OF CHEESE-MAKING 

SYSTEM OF KEEPING RECORD OF THE 
OPERATIONS OF CHEESE-MAKING 

Few manufacturing processes require more careful 
and more skilled mechanical manipulation than does 
cheese-making ; none demands more responsibility and 
intelligence. A successful cheese-maker must be quick 
to think and to act; he must know the details of 
his process and the principles underlying these de- 
tails, and be able to apply his knowledge in con- 
trolling variations caused by climatic, biological and 
chemical conditions. In beginning liis daily work, 
a maker should have clearly in mind the ideal 
he wishes to realize in the finished cheese, and 
should conduct his work with this end in view. It is 
absolutely essential to the highest success to keep daily 
records of the details of the work for constant refer- 
ence. Below, we give a detailed blank form, and 
advise all cheese-makers and students of cheese- 
making to make constant and faithful use of it in 
their daily work: 

1 . Vat used (number of vat) . 

2. Condition of milk (flavor, temperature, acidity). 

3. Amount of milk in vat pounds. 

4. Fat in milk per cent. Casein in milk per cent. 

5. Ripeness of milk by — 

1. Acidity-test per cent of acidity. 

2. Marschall rennet- test spaces. 

3. Monrad rennet-test seconds. 

6. Kind of starter used Acidity per cent. 

7. Amount of starter used pounds. 

8. Time when starter was added a. m. p. m. 

9. Amount of color added. 

10. Kind of color used. 

11. Temperature of milk when rennet was added degrees F. 

12. Ripeness of milk when rennet was added — 

1. By rennet-test seconds or spaces 

2. By acidity-test per cent. 

13. Time when rennet was added a. m. p. m. 

14. Amount of rennet (or pepsin) used ounces or grams. 

15. Amount of rennet (or pepsin) used per 1,000 pounds of 

milk ounces or grams. 

16. Time when curd was cut a. m. p. m. 

17. Time in coagulating minutes. 



FIRST STEPS IN CHEESE-MAKING I7 

18. Condition of curd when cut (hard, soft, etc.). 

19. Time when heating began a. m. p.m. 

20. Acidity-test of whey when heating began per cent. 

21. Temperature to which milk was heated after cutting, etc degrees f! 

22. Time at which temperature was reached a. m. p. m. 

23. Test when whey was removed — 

1. By hot-iron test inches. 

2. By acidity-test per cent! 

24. Time at which whey was removed a. m. p. m. 

25. Time from cutting curd to removal of whey hours minutes 

26. Amount of fat in whey per cent. 

27. Condition of curd (sweet, tainted, solid, gassy, floating, etc.). 

28. Time when curd was milled a. m. p. m. 

29. Length of string on hot iron when curd was milled inches. 

30. Acidity- test of whey-drippings when curd was milled per cent. 

31. Time when curd was salted a. m. p. m. 

32. Acidity-test of whey running from curd just laefore salting per cent. 

33. Amount of salt used for 1,000 pounds of milk pounds. 

34. Kind of salt used. 

35. Time when curd was put in press a. m. p. m. 

36. Temperature of curd when put in press degrees F. 

37. Condition of ciu"d when put in press. 

38. Kind of cheese made. 

39. Number of cheeses made. 

40. Time when cheese was dressed a. m. p.m. 

41. Time when cheese was pressed a. m. p. m. 

42. Time when cheese was taken from press a. m. p. m. 

43. Weight of green cheese pounds. 

44. Average amount of milk per pound of cheese pounds. 

45. Amount of cheese from 100 pounds of milk pounds. 

46. Amount of cheese made for 1 pound of milk-fat pounds. 

47. Weather conditions (temperature, humidity etc.). 

48. Amount of cheese from 100 pounds of milk calculated by 

formula 6 (p. 225). 

Special remarks. — (Include here any deviations from the usual modes 
of procedure not included in the foregoing list.) 



FIRST CARE OF MILK AT THE FACTORY 

Each can of milk, on arriving at the factory, should 
be carefully examined for acidity, cleanliness and ab- 
normal flavors (p. 426). If any is sour or of bad 
flavor it should not be accepted. When any patron's 
milk is suspected, from the results of these tests, of 
containing ferments that work harm in cheese-making, 
the milk should be subjected to the fermentation test 
(p. 434)- At any time when abnormal fermentations 
make trouble, each patron's milk should be thus 
treated until the source of trouble is located. For a 
quick test for acidity, see p. 428. When weighed, the 



l8 SCIENCE AND PRACTICE OF CHEESE-MAKING 

milk should be strained through two layers of clean 
cheese-cloth to remove all insoluble dirt (p. 431). 
While the milk is accumulating in the vat, it should 
be stirred frequently up to the time of coagulating 
with rennet in order to keep the cream from separ- 
ating. When the vat is full enough, the amount of 
milk present is figured, and the acidity of the milk 
is determined or a rennet-test made. 

RIPENING MILK 

This consists in the formation of a certain amount 
of lactic acid (p. 292). Its object is to control more 
completely the various operations of cheese-making; 
this is accomplished especially (i) by the repression 
of abnormal ferments; (2) by assistance in shrinking 
curd, expelling whey, and maturing the curd in body 
and texture. Lactic acid may be formed by allowing 
milk to stand a while at a temperature of about 86° F. 
When lactic acid bacteria are not present in abundance 
or are kept back in growth by injurious organisms, it 
is necessary to use a starter. 

Preparation of starter. — A starter is a material 
(usually milk) containing lactic acid and large num- 
bers of lactic acid organisms added to milk or cream 
for the purpose of causing lactic fermentation. Start- 
ers are of two kinds: (i) Natural and (2) com- 
mercial, (i) Natural starters. — A natural starter 
may be prepared as follows : Milk of the best possible 
character, taken under precautions necessary to insure 
cleanliness, is heated to 90° F. for one hour, aerated in 
a pure atmosphere, and immediately cooled to 65° F. 
In 24 hours the milk should be sufficiently sour to be 
ready for use. Some of this starter may be used in 



FIRST STEPS IN CHEESE-MAKING I9 

preparing a starter for the following day, putting a 
little into some skim-milk that has been heated to i8o° 
F. for 30 minutes, cooled to 70° F., and then allowed 
to stand 18 to 24 hours. The starter may thus be 
propagated from day to day. Occasionally, almost 
pure cultures of lactic acid bacteria can be obtained 
in this way, but this is an exceptional experience. 
Results much more reliable come from the use of 
commercial starters. (2) Commercial starters. — Com- 
mercial starters are special preparations consisting of 
certain organisms that produce lactic acid. These are 
carefully prepared under the supervision of trained 
bacteriologists and sold to cheese-makers. They are 
usually known as cultures or pure cultures. The 
medium in which these organisms are sent out may 
be milk, broths, milk-sugar or porous paper. Proper 
directions, with necessary precautions, usually ac- 
company these commercial preparations. Below is 
given a satisfactory method for the use of a com- 
mercial preparation in making a starter for cheese- 
making. 

Inoculation of the culture. — In a can or glass ves- 
sel that has been thoroughly cleaned and sterilized 
with boiling water, place one quart of clean, sweet 
milk. Heat the milk to at least 185° F. for one hour 
by placing the can or vessel In boiling water. At the 
end of an hour cool the milk rapidly to 95° F. by 
setting the can or vessel in cold water. Then add the 
contents of the small bottle of a prepared culture to 
the milk, stirring It In with a sterilized spoon. Allow 
the milk to cool gradually to 70° F. and hold at this 
temperature for 24 hours. At the end of this time 
the milk should be sour and coagulated. 



20 SCIENCE AND PRACTICE OF CHEESE-MAKING 

Propagation of starter. — In a can that has been 
thoroughly cleaned and sterilized, place two gallons of 
clean, fresh skim-milk. Heat the milk to 185° F. for 
one hour by setting the can in boiling water. Stir 
the milk frequently to insure even heating. After the 
milk has been held at this temperature for one hour, 
it may be cooled immediately to 70° F. by placing 
the can in cold water. Then add the contents of the 
small vessel that was prepared on the previous day, 
stirring it in with a sterilized spoon. Hold the tem- 




FIG. 6 — THIS STYLE OF DIPPER HAS A SOLID HANDLE 
AND IS EASY TO KEEP CLEAN IN EVERY PART 

perature at 70° F. for 18 hours. At the end of this 
period the milk should be sour and firmly coagulated. 
A uniform starter can thus be prepared from day to 
day, always adding enough of the coagulated starter 
to the amount of pasteurized skim-milk necessary for 
the cheese-making process. 

Precautions. — All vessels, pails, dippers, thermome- 
ters and everything with which the starter-milk comes 
in contact should be sterilized before being used. 
Starters should not be prepared from the milk mixed 
in the vat or from whey. A good starter is an in- 
valuable aid In cheese-making, while a bad one is a 
sure source of trouble. As soon as the starter loses 



FIRST STEPS IN CHEESE-MAKING 21 

its clean, nutty, mild aroma and sharp taste, it should 
be replaced by a new one. 

Use of starter in cheese-making. — The amount of 
starter that can safely be used will depend on the 
amount of acidity or ripeness of the milk at the start. 
Generally, from 0.5 to 2 per cent is sufficient, but, if 
the milk is very sweet, as much as 5 per cent can 
be used. In using- a starter, reject the upper portion 
and pass the rest into the milk through a fine strainer. 
If colored cheese is being made, add the starter before 
the color; otherwise white spots in the curd may be 
produced. 

Finding proper degree of ripeness. — The proper 
degree of ripeness can be ascertained by the following 
methods : 

(i) By the use of the test for acidity (p. 426) ; 

(2) by the use of the Marschall rennet-test (p. 429) ; 

(3) by the use of the Monrad rennet-test (p. 431). 

The general aim of ripening is to have such a degree 
of acidity when the rennet is added that the curd will 
remain in the whey not more than 2^ to 3 hours. 
This time will vary with the seasons of the year, the 
important point being to have the curd firmed in the 
whey before too much acidity has developed. Usually 
when the acid test shows 0.19 to 0.21 per cent of 
acidity, or when the milk coagulates at 2^ spaces in 
the Marschall rennet-test, or in 45 to 60 seconds by 
the Monrad test, the proper degree of ripeness has 
been reached. Milk testing over 0.21 per cent acidity 
when delivered at the factory is generally overripe and 
liable to cause trouble ; therefore, it should not be ac- 
cepted, unless most of the other milk delivered at 
the time has considerably less acidity. 



22 SCIENCE AND PRACTICE OF CHEESE-MAKING 

ADDING COLOR 

When coloring-matter is used, it should be added 
just before the rennet, being diluted before addition 
and thoroughly mixed through the mass of milk. The 
amount used depends on the demands of different 
markets. About i ounce for i,ooo pounds of milk is 
generally sufficient, but the amount may vary from 
Yz ounce to 3 ounces. 

PREPARATION AND ADDITION OF 
RENNET-EXTRACT 

Adding rennet-extract is commonly known as 
^setting" milk with rennet. As soon as the milk is 
ripe enough the rennet-extract should be added. In 
the use of rennet, three points must be kept in mind: 
(i) Temperature of milk; (2) amount of rennet- 
extract to use; (3) method of adding rennet-extract 
and thorough stirring after addition. 

(i) Temperature of the milk. — The ideal tem- 
perature, under normal conditions, is 86° F., al- 
though many successful cheese-makers prefer a 
temperature of 84° F. At higher temperatures 
the curd hardens too quickly to handle conven- 
iently, and there is danger of loss of fat later in the 
cutting. Lower temperatures require a longer time 
for a proper degree of hardness, and, if the extra 
time is not allowed, give too soft a curd, which 
results in loss in cheese yield. The temperature 
should be uniform throughout the milk. 

(2) Amount of rennet-extract to use. — This will 
depend on (i) the strength of the extract, (2) the 



FIRST STEPS IN CHEESE-MAKING ^3 

temperature of the milk, (3) the acidity of the milk, 
(4) the composition of the milk, (5) the kind of 
cheese to be made, and (6) the temperature of 
curing (p. 61). In general, an amount sufficient 
to coagulate the milk fit for cutting in 25 to 35 
minutes should be used. Generally from 2^ to 4 
ounces for 1,000 pounds of milk will suffice. 

(3) Method of adding rennet-extract and subse- 
quent treatment. — Before being added to milk, the 
rennet should be diluted with 40 times its volume 
of pure, cold water. The object of this is to enable 
one to distribute the rennet solution thoroughly 
and uniformly throughout the mass of milk before 
the rennet begins to coagulate the casein. Rennet 
acts more slowly when diluted with cold water 
(p. 307). The milk should be thoroughly stirred 
before the rennet is added. The diluted rennet 
should be gradually poured the whole length of 
the vat, and the milk at once stirred again for 3 
to 5 minutes. A rake may be used to advantage 
for stirring. Then the surface is stirred gently to 
keep the cream from rising. All motion of the 
milk should be stopped as soon as, or before, coag- 
ulation starts. The vat should be covered to pre- 
vent cooling at the surface and to keep out flies 
and dust, and then left undisturbed until ready for 
cutting. 

Causes of imperfect coagulation. — By imperfect 
coagulation, we mean (i) incomplete or delayed 
coagulation of casein, shown by slimy or gelatin- 
ous appearance of the coagulated milk and a curd 
containing too much whey; or (2) variation in de- 
gree of hardness in different portions of the mass 



24 SCIENCE AND PRACTICE OF CHEESE-MAKING 

of milk, some portions being too hard and others 
too soft. Imperfect coagulation results (i) in 
excessive loss of fat and of casein from the soft 
curd and (2) in imperfect texture and body in 
cheese, due to the larger amount of whey retained 
in the hard pieces of curd. 

The causes of imperfect coagulation may be: 

(1) For incomplete or delayed coagulation: 

(a) Jarring of milk after coagulation starts. 

(b) Weak rennet-extract or too small an amount. 

(c) Low temperature, due to inaccurate thermometer 
(p. 309). 

(d) The presence of formalin (p. 308). 

(e) Abnormal milk, containing small percentage of 
casein or small percentage of calcium salts (p. 164). 

(f) Pasteurized milk (p. 310). 

(g) Presence of abnormal bacterial ferments, 
(h) Heavily watered milk (p. 307). 

(i) Use of badly rusted milk-cans (p. 309). 

(2) For uneven coagulation: 

(a) Uneven temperature of milk in vat, due to lack of 
thorough agitation. 

(b) Adding rennet to milk too soon after heating, while 
the sides and bottom of the vat are still hot. The curd sticks 
to the sides of the vat and makes cutting difficult. 

(c) Agitation of milk after coagulation begins. 

(d) Uneven distribution of rennet -extract. 



CHAPTER III 

Operations from Cutting Curd to Salting 

CUTTING THE CURD 

Purpose of cutting curd. — The object of cutting 
curd is to allow the whey to escape from it. The 
rapidity with which this occurs increases with the 
smallness of the pieces. 

When to cut curd. — Curd must be cut at the 
right stage of hardness. The stage for cutting is 
ascertained in several ways. We give three of 
them. ( I ) The end of the index finger is inserted 
obliquely into curd half an inch or more and then 
slowly raised to surface. If the curd breaks apart 
with a clean fracture without leaving small bits 
of curd on the finger, and if the whey in the broken 
surface is clean and not milky, the curd is ready 
to cut. (2) Lay the back of the hand, including 
the fingers, on the surface of the curd near the 
edge of the vat and press it gently away from the 
side of the vat. As soon as it will separate from 
the side of the vat in a clean way, leaving no par- 
ticles of curd on the side of the vat, it is ready to 
cut. (3) The following is probably the most ac- 
curate rule for determining when the curd should 
be cut: Tzvo and one-half times the period from add- 
ing rennet till the first thickening appears gives the 
time for cutting. 

25 



26 SCIENCE AND PRACTICE OF CHEESE-MAKING 

Example: 

Time when rennet was added, 7 130 a. m. 
Time of first thickening, 7 140 a. m. 
From adding rennet till first thickening=io min- 
vites. 

,23^ times 10 minutes:^25 minutes. 

7:30+25=7:55. 

Time of cutting is 7:55 a. m. 

When curd is cut too soon, the loss of fat, and 
probably of casein, is increased and there is a 
smaller yield of cheese. If the curd becomes too 
hard, it cannot be cut uniformly; if a wire knife 
is then used, the wires may break. 

How to cut curd. — Uniformity in the size of 
pieces is the aim of good cutting. This can be 
most easily accomplished by cutting slowly length- 
wise of the vat with a ^-inch steel horizontal 
knife having sharp edges. Then cut crosswise 
with a 5-16-inch perpendicular, wire knife. Finally, 
cut lengthwise with the same wire knife. Care 
should be taken not to smash the curd when insert- 
ing the knives or when turning them at the ends 
of the vat. The resulting cubes should be of uni- 
form size to insure an even escape of whey, a 
well-regulated development of acidity in curd and a 
uniform color in the cheese. Extra losses of cheese 
constituents (p. 193) in the whey are due to care- 
lessness or lack of skill in the cutting or in the sub- 
sequent stirring. The knives should be drawn 
straight and even and should not overlap the por- 
,tions previously cut. The faster the - cutting, the 
smaller and more uneven the cubes will be. 



CUTTING CURD TO SALTING 27 

Effect of cutting curd fine or coarse. — The effect 
of cutting curd fine is to release the whey more 
rapidly and completely and to produce a cheese 
containing- less moisture. This fact is made use 
of in the handling of overripe milk (p. 122) ; the 
quick escape of whey enables one to control better 
the acidity in the curd. Curd must be heated to 
a certain temperature for a certain length of time 
before it becomes firm enough to insure good body 
in the cheese. If the pieces of curd are larger, 
it takes longer for the whey to escape and longer 
for the pieces to contract and become firm. Con- 
sequently, if knives that cut coarser are used, the 
rennet must be added when the milk shows less 
acidity, in order to allow the curd to remain in the 
whey a longer time. 

Behavior of curd after being cut. — After the curd 
is cut into small cubes, a slight coating or film 
begins to form on the outer surface of each cube. 
The existence of this film can be shown by break- 
ing one of the curd cubes ; the film can then be 
seen. The inner portion of the curd is observed 
to be softer, due to the larger amount of whey 
present. It is important that this film should not 
thicken or harden too rapidly and thus prevent 
the escape of whey in desired amount. The sub- 
sequent operations have for one of their important 
objects control of the expulsion of whey and simul- 
taneous hardening or contracting of the pieces of 
curd. The contraction or hardening of the pieces 
of curd is known as "firming." It is probably due 
primarily to escape of whey. What share tem- 
perature, rennet and acidity each has in the process 
cannot now be stated definitely. 



28 SCIENCE AND PRACTICE OF CHEESE-MAKING 

STIRRING CURD AFTER CUTTING 

If the curd is not stirred immediately after cut- 
ting, it soon masses together or becomes himpy. 
To prevent this, the curd must be kept in motion 
till the pieces become properly firmed. Tlie stir- 
ring of the soft, tender curd should be very gentle 
at first and should be done with an agitator (Fig. 
7). In large factories, steam-power agitators are 
used. After the pieces of curd become healed over 
on the surface by the formation of the film de- 




FIG. 7 — MCPHERSON HAND-AGITATOR FOR STIRRING 
CURD IMMEDIATELY AFTER CUTTING 

scribed above and start to contract, they can be 
stirred and kept separated more easily by usins; a 
wooden rake (Fig. 8). The curd should be pre- 
vented from collecting in the corners of the vat and 
from sticking to the sides. Rough handling of the 
soft curd crushes it and causes a severe decrease in 
the yield of cheese, as the result of increased loss of 
cheese-solids in the whev. 



CUTTING CURD TO SALTING 29 

HEATING THE CURD 

When to apply heat. — The rapidity with which 
the pieces of curd contract and the rapidity with 
which the lactic acid is being formed determine 
the time at which the heat should be applied. In 
any case, the curd should be stirred gently for 
some time after cutting, until the small pieces have 
healed over, or formed a film, and have contracted 
slightly. Heat alone does not firm the curd. It 
is probably due to the combined action of heat, ren- 




FIG. 8 — DOUBLE-TOOTHED CURD-RAKE USED FOR 
STIRRING CURD AFTER CUTTING 

net and acidity. The firming and contraction of 
curd and expulsion of whey go on together. The 
faster the acidity is increased, the quicker will the 
curd contract. The action of heat in the process of 
contraction enables the curd to retain its firmness 
and also prevents the reabsorption of whey. 

How high to heat curd. — The lower the tempera- 
ture used for heating curd, provided the curd be 
properly firmed, the smoother will be the body of 
the cheese. As a rule, 98° to 100° F. will be high 



30 SCIENCE AND PRACTICE OF CHEESE-MAKING 

enough, but this can be varied from 96° F. in the 
springtime to 102° F. in the fall. Curd from milk 
rich in fat is harder to firm than curd from poor 
milk, owing generally to the smaller proportion 
of casein relative to fat. Thus, milk containing 
3 to 3.6 per cent of fat ordinarily behaves at 94° to 
96° F. the same as milk with 4 to 5 per cent of fat 
does at 98° to 102° F. In extreme cases, the 
temperature may have to be raised even higher to 
firm successfully the curd from overripe milk. High 
heating generally causes a corky or rubbery-bodied 
cheese. 

How to regulate heat. — Care must always be 
taken not to raise the temperature of the curd too 
rapidly. Usually the temperature can be raised 
about 2° F. in every 5 minutes, but when the lactic 
acid formation is slow, 1° F. every 5 minutes may 
be sufficient. The following rule is a reliable guide 
in heating: 

Ritle for heating. — If, after cutting, the whey 
around the curd shows 0.12 per cent acidity, allow 
60 minutes for heating; 0.13 per cent acidity, al- 
low 40 minutes for heating; 0.14 per cent acidity, 
allow 30 minutes for heating; 0.145 acidity, allow 25 
minutes for heating; 0.15 per cent acidity, allow 20 
minutes for heating. 

It is noticeable that the whey at this stage con- 
tains 0.05 to 0.08 per cent less of acidity than the 
milk does when the rennet is added. This is due 
to the fact that the whey contains no casein and the 
casein in the milk has the power of acting like an 
acid in neutralizing alkali. 



CUTTING CURD TO SALTING 3I 

Applying heat too fast hardens the outside of the 
curd and prevents the escape of whey. The acid 
in the curd develops from the sugar present in the 
whey within the curd and not from the whey out- 
side of the curd^ so that^ if too much whey is re- 
tained in the curd, too much acidity develops and 
an acid or sour cheese results. 

WHEN TO REMOVE WHEY FROM CURD 

How to ascertain. — Several indications show 
when the whey should be removed from the curd, 
(i) The pieces of curd should be contracted to 
less than one-half their original size. (2) They 
should be firm and rubber-like, or springy, so that 
when a mass of curd is pressed between the hands 
and then suddenly freed from pressure, the pieces 
should fall apart at once and show no tendency to 
stick together. (3) When firm, the curds should 
show fine threads yg inch long when rubbed on a 
clean, hot iron (p. 438). (4) The whey around 
the curd should have 0.16 to 0.18 per cent of acid- 
ity, as shown by the acid test. This will vary 
slightly, depending on the time required for re- 
moving the whey. The quantity of milk in the vat, 
the size of the outlet of the vat, and the condition • 
of the curd should govern the amount of acidity 
developed at the time of starting to remove the 
whey. It is a good practice to draw off the whey 
down to- the level of the curd in the vat a few min- 
utes before sufficient acidity has developed. This 
gives a better chance to control the remainder. 
The most accurate rule to follow is to have 0.24 



32 SCIENCE AND PRACTICE OF CHEESE-MAKING 

to 0.30 per cent of acidity in the whey running 
from the curd after it has been stirred dry enough 
and piled up for cheddaring. The amount of acidity 
developed will depend on the character of cheese 
desired and upon the amount of moisture left in the 
curd. A firm export cheese requires more acidity 
and less moisture than a quick-ripening cheese for 
home trade. 

STIRRING CURD TO DRY IT 

The proper place to stir and to dry the curd is 
in the whey, from the time the whey has reached 
the curd level until it is all removed. This gives 
a brighter and better color to the curd and re- 
quires less labor than when stirring is delayed 
until all whey has been removed. If the curd is 
not properly firmed, vigorous hand-stirring may 
cause serious loss of fat here. Too much free whey 
should not be left around or in the pieces of curd 
at this time, as it enables lactic acid to develop too 
fast, owing to the presence of the milk-sugar in the 
whey (p. 45). 

CHEDDARING THE CURD 

This operation is the main distinctive feature of 
the cheddar method of cheese-making. It consists 
essentially of two operations or a continuation of 
one operation in two stages : ( i ) Piling or matting 
of curd and (2) cutting curd into strips and con- 
tinuing the operation of piling and repiling. 

Piling or matting curd. — As soon as the curd has 
been stirred enough to become sufficiently dry, it 



CUTTING CURD TO SALTING 33 

should be piled evenly along the two sides of the 
vat, with an open channel 4 to 6 inches wide be- 
tween the piles, to facilitate the ready drainage of 
the whey that comes from the curd. The vat should 
have dip enough to enable the escaping whey to 
pass away rapidly and keep it from lying in pools 
around the curd. Up to this time the curd should 
not have been allowed to become lumpy, but, as 
far as possible, the small pieces should be kept 
separated. This results in a more uniform expul- 
sion of whey, a more uniform development of acid 
and a more uniform color in the curd. Some 
cheese-makers use curd-sinks to dry the curd in 
during this stage. Others use strainer-racks on the 
bottom of the vats. In using these, the curd and 
whey are dipped in pails on to the racks, which are 
covered with cheese-cloth. The whey drains 
through the racks and the curd is easy to stir. The 
curd-sinks and vat-racks are of some aid in han- 
dling curd from overripe milk, but under normal 
conditions they have no particular advantage over 
the vat. 

Cutting and repiling curd. — As soon as the curd 
has become matted together sufficiently, forming 
a solid mass about 6 inches deep, it should be cut 
into blocks or strips 6 to 8 inches wide and turned 
over, the top going on the bottom. This takes 15 
to 20 minutes from the time of piling. If the curd 
contains excessive amounts of visible or free whey, 
the blocks should be cut very narrow and turned 
as soon as matted. After draining about 15 min- 
utes, the strips are piled in layers two deep, each 
time the upper part being turned down. The blocks 



34 SCIENCE AND PRACTICE OF CHEESE-MAKING 

are then turned every 15 minutes until the opera- 
tion is completed. After a while the strips may be 
piled in deeper layers. The repiling is performed 
again and again, always exposing to the air the 
portions that were turned inside on the previous 
piling, in order to keep the temperature uniform 
through the mass. The operation is hastened by 
piling the strips two or three layers deep. If the 
curd is very moist and the formation of acid goes 
on quickly, it is not advisable to pile the blocks in 
deep layers. It is better to separate them so that 
they will dry out as soon as possible. 

Object of cheddaring operation. — The object of 
the cheddaring operation is to accomplish two re- 
sults : ( I ) The formation of a curd containing less 
water by the removal of whey; and (2) the forma- 
tion of a characteristic body and texture in the 
curd. The physical -condition of the curd changes 
from a tough, rubber-like consistency with a high 
water content to a mass having a smooth, velvety 
appearance and feeling, and a softer, somewhat 
plastic consistency. The texture also changes so 
that the curd acquires a peculiar fibrous condition, 
or grain, tearing off somewhat like the cooked 
meat of a chicken's breast. Along with these 
changes the curd forms longer strings on a hot 
iron, usually an inch or more after the cheddaring 
has continued for some time. Some chemical 
changes appear to take place in the proteins. The 
changes noted above are due to the formation of a 
substance in the curd which is dissolved in warm, 
5 per cent brine (p. 147) • This substance in pure 



CUTTING CURD TO SALTING 35 

condition forms very long strings when warm. 
(Figs. 32 and s^, p. 148.) 

Completion of the cheddaring process. — The 
cheddaring process is regarded as complete when 
we have the following conditions: (i) The curd 
forms strings on a hot iron an inch to an inch and 
a half in length. (2) The whey running from the 
curd shows an acidity of 0.65 to 0.90 per cent, de- 
pending on the whey content of the curd and the 
manner in which it is cheddared. (3) The curd 
should be velvety in appearance and feeling, and tear 
apart like the breast-meat of a chicken. 

MILLING CURD 

When the cheddaring process is complete, as 
determined by the tests given, the curd is ready to 
mill. The objects of milling are to cut the curd 
into small pieces of uniform size, in order that the 
curd may be salted more evenly and handled more 
easily in salting during the rest of the cheese- 
making process ; and also to permit the escape of 
more whey. In cheddaring the curd, it should be 
piled so that, wdien ready, the strips will be in 
convenient shape and size for milling. The mill 
should cut the curd into small pieces of uniform 
size, and should do it without crushing or squeez- 
ing the milk-fat from the curd. If a steam-power 
curd-mill is used, it should not be run too rapidly, 
for it will cut the curd unevenly and the texture 
of the cheese will be poor. After milling, the pieces 
of curd should be well stirred, kept apart, and freely 
exposed to fresh air. At this stage the freshly cut 
surfaces afford an excellent channel for the escape 



36 SCIENCE AND PRACTICE OF CHEESE-MAKING 

of gases and undesirable flavors. The airing and 
stirring are made easy by the use of forks. 

After milling, the curd is piled up in order to 
flatten out pin-holes, if any, and stirred enough to 
keep it from matting together. The softening of 
the curd continues after milling, along with the fur- 
ther formation of lactic acid. The curd should be 
kept warm all the time. 

If the operations up to this time have been prop- 
erly managed, the whey remaining in the curd has 
become a part of it to such an extent that not a 
drop can be squeezed by pressure of- the curd in 
the hand. If, however, the whey has not become 
perfectly incorporated with the curd-solids, more or 
less free or unassimilated whey is found Inside the 
original, small pieces of curd; and, when these are 
broken in the milling, white whey runs out of the 
curd, involving considerable loss of fat. 



CHAPTER IV 

Operations from Salting Curd to Removal 

from Press 

SALTING CURD 

When to apply salt. — After the pieces of curd 
have become well contracted and feel silky and 
mellow, they are ready to be salted. The curd at 
this stage should show by the hot-iron test strings 
i^ inches long, but this test cannot be relied upon, 
as most curds become more or less greasy after mill- 
ing, and do not so easily stick to a hot surface. A 
test of the whey exuding from the curd is much 
more reliable. It should have 0.90 to 1.2 per cent 
of acidity, as shown by the acid test. This is the 
most reliable test for indicating when curd is ready 
for salting, and it is equally useful at other stages ; 
but students and cheesemakers should be familiar 
with the use of all tests. 

It is often a difficult matter to tell just when a 
curd is in the best condition for salting, and this 
knowledge comes only as the result of long expe- 
rience. Generally, the curd smells like toasted cheese 
when rubbed on a hot iron ; and, when squeezed be- 
tween the hands, a certain amount of fat may start, 
but these tests are not reliable. The per cent of 
acidity allowed to develop before salting depends 
on the condition of the curd and also the conditions 
of temperature and moisture under which the cheese 

37 



38 SCIENCE AND PRACTICE OF CHEESE-MAKING 



is to be stored and ripened. If the cheese is to be 
kept for any length of time in a hot room, the de- 
velopment of acidity should be greater and the curd 
more matured. This is especially true if the curd 
is gassy or weak-bodied. If the curd is free from 
gas, and the cheese is to be kept in cold storage till 
ready for consumption, the acidity need not be so 
great ; but, in any case, it should be sufficient to insure 
a mellow body in the cheese. 

Amount and kind of salt to use. — The amount of 
salt used depends on (i) the amount of whey in the 
curd, (2) its acidity, and (3) the type of cheese 
desired. For ordinary factory milk, from i^ to 2^ 
pounds of salt for 1,000 pounds of milk used will 
be sufficient, but in extreme cases these limits 
may be exceeded. A moist curd is usually salted 
more. The weight of milk, however, is not an ac- 
curate basis for determining the amount of salt to 
use. It is much better to use the weight of curd 
or the percentage of fat in milk as indicated below. 



Assuming 


that curd ready for 


salting 


contains 


Per cent of 




From 1 ,000 pounds of milk 
Pounds of milled curd con- 


Amount of salt to use 


fat in milk 




taining 40 per cent of water 


Lbs. '^ 


Uzs. 


3.0 




87.4 


1 


12 


3.1 




89.8 


1 


13i 


3.2 




92.2 


1 


15 


3.3 




94.6 


2 


i 


3.4 




97.0 


2 


2 


3.S 




99.4 


2 


H 


3.6 




101.8 


2 


5 


3.7 




104.2 


2 


6i 


3.8 




106.6 


2 


8 


3.9 




109.0 


2 


H 


4.0 




111.4 


2 


11 


4.1 




113.8 


2 


12i 


4.2 




116.2 


2 


14 


4.3 




118.6 


2 


15i 


4.4 




121.0 


3 


2 


4.5 




123.4 


3 


3* 



SALTING TO TAKING FROM PRESS 39 

about 40 per cent of water, i,ooo pounds of milk 
would furnish about the amounts of curd for the dif- 
ferent percentages of fat in milk shown on page 38. 

Salt of fairly coarse grain is preferable, because 
it dissolves more slowly and penetrates the curd 
more thoroughly. Special brands of cheese salt are 
prepared by manufacturers and are generally shipped 
in paper-lined barrels. 

How to apply salt. — The curd should be spread 
out thinly over the bottom of the vat, and, if neces- 
sary, cooled to 90° F. Both curd and salt should 
be free from lumps. The salt should be put on in, 
at least, three applications, and each time should 
be evenly distributed over the surface. After each 
sprinkling of salt, the curd should be well stirred 
with forks. Applying salt too rapidly or all at once 
hardens the outside of the small pieces of curd and 
hinders its absorption. A fine hair or copper sieve 
is of considerable aid in regulating the application 
of salt. Salt in cheese affects flavor, body, texture 
and keeping quality (p. 343). 

Effects of salting.-7-While salt is added mainly 
for the sake of the taste it gives to cheese, it pro- 
duces other effects, such as (i) aiding in removal of 
whey; (2) hardening and contracting the curd; 
(3) checking or retarding the formation of lactic 
acid; and (4) checking undesirable forms of fer- 
mentation. An unsalted cheese cures more rapidly 
and is apt to develop a bitter flavor, the intensity 
increasing with increase of ripening temperature. 
Excessive salting makes a cheese mealy, because 
too dry, and it cures slowly. Much of the salt 
added passes into the whey. Green cheese normally 



40 SCIENCE AND PRACTICE OF CHEESE-MAKING 

salted contains 0.6 to i per cent of salt, and this 
increases somewhat in the ripened cheese, through 
loss of moisture (p. 344). 

An increased quantity of salt is of advantage in 
correcting such defects as gassy, highly acid, or very 
soft cheese. Excessive loss of fat may often be 
avoided by the early addition of salt, which hardens 
the surface of the pieces of curd and prevents further 
exudation of fat. 

PRESSING CURD AND DRESSING CHEESE 

Condition and temperature of curd when ready 
for press. — Before the curd is placed in the hoops, 
the salt should be completely dissolved ; the curd 
should feel mellow and silky. No fixed pressing 
temperature can be prescribed even for normal 
curd, since there are several variable factors which 
we must take into consideration. We can say that, 
in general, under ordinary, normal conditions, the 
temperature should be not much above 80° F., with 
a range of variation from 78 to 85° F., according to 
certain conditions, among the most important of 
which are the following: (i) Size of cheese made; 
(2) temperature of room; (3) condition of curd; 
and (4) rate at which pressure is applied. Small- 
sized cheese, such as Young Americas, Prints and 
Picnics, should be put in press warmer than larger- 
sized cheese, since they cool more rapidly. During 
early spring, late fall, and winter months, the press- 
ing temperature should be higher than during the 
summer months. During the hot weather of sum- 
mer, it may be necessary to cooJ the rurd before 



SALTING AND TAKING FROM PRESS 4I 

pressing, which can be done by running cold water 
around the outside of the vat, or by placing the curd 
'in a cold room for a short time. One can usually 
allow a somewhat wider range in the pressing tem- 
perature when handling a normal curd than in the 
case of one which is noticeably defective, such as a 
greasy or a harsh curd. The faster a curd is put 
into the hoop and pressed, the lower the temperature 
it may be permitted to have. 

The effects of pressing at too high a temperature 
are the following: (i) Excessive loss of fat and 
consequent loss of yield; (2) the pieces of curd be- 
come greasy on the outside and do not stick to- 
gether perfectly, which results in producing cheese 
of less close texture on account of the increased 
number and size of the mechanical-holes; (3) greasy 
curd prevents bandage sticking to cheese; (4) high 
temperature favors development of gas and conse- 
quent huffing; (5) the loss of fat has the same 
effect as skimming milk, as it makes the cheese too 
dry. 

The effects of pressing at too low temperature are 
the following: (i) The pieces of curd do not stick 
together perfectly, resulting in cheese of open texture 
and imperfect rind formation, which affords an op- 
portunity for entrance of mold and skippers; (2) it 
may sometimes cause a mottled appearance when a 
sample is drawn by a cheese-trier; (3) the cheese 
retains more whey. 

Object of pressing curd. — The object of pressing 
curd is to give the cheese a convenient form for 
handling and a definite, characteristic shape for 
market, and not alone to squeeze out whey, which 



42 SCIENCE AND PRACTICE OF CHEESE-MAKING 

should be removed mostly while the curd is in the 
vat. Pressing will not make a close-textured cheese, 
if the curd is gassy or too sweet. If the cheese is 
to be close in texture, the curd must be full matured 
before salting. 

Preparing hoop for receiving curd. — A round cot- 
ton cap-cloth of the size of the hoop is wrung out 
of hot water and placed in the bottom of the hoop. 
The bandage is then placed in the hoop, with 
the edge turned in evenly about one inch on 
the bottom. The curd is weighed in order to in- 
sure a uniform size of cheese and is then put into 
the hoop. The hoops should not be filled too full, 
since the curd will be squeezed out around the top 
when pressed. A cotton cap-cloth is then placed 
over the top of the curd, and then the ring and 
follower. Steel rings and followers are preferable 
to fibrous rings and wooden followers. They are 
more sanitary, easier to clean, are not absorbent, and 
do not contract and expand in hot weather. 

Applying pressure. — When the curd is put in 
press in normal condition, a moderate pressure will 
cause the pieces of curd to cement together in a 
smooth, solid mass. The pressure should be uni- 
form and continuous for 24 hours. With a screw- 
press, the pressure Is applied lightly and gradually 
at first, full pressure being reached In about 15 
minutes, and the press is tightened as fast as the 
screws become loose, especially during the first 
hour. After the curd has been in the press 45 to 60 
minutes, it should be firmly cemented and ready for 
dressinsf. 



SALTING TO TAKING FROM PRESS 43 

Dressing cheese. — Too much care cannot be taken 
in finishing a cheese for market. The appearance 
greatly influences an intending purchaser. As soon 
as the cheese is sufficiently pressed, it is taken from 
the hoop and placed on a dressing-bench. The 
bandage is pulled up, made free from wrinkles, and 
trimmed to about one inch on each end with a sharp 
knife. A starched cap-cloth is placed on each end, 
outside the bandage. Over these, the cotton cloths 
are placed, and the cheese is then returned to the 
hoop, where it is left until the following morning. 
The cheese should then be taken from the press 
and examined for imperfections in finish ; if any are 
present, they should be remedied and the cheese 
then returned to the press until the hoops are re- 
quired for use again. It is better to have the cheese 
in the hoops under pressure for 48 hours than for 
only 24. 

Plenty of hot water and clean, soft press-cloths 
should be used to insure a good rind on the cheese. 
Some cheese-makers place a cotton cloth around 
the entire side of the cheese. This improves the 
rind and protects the surface from any dirt or rust 
marks that may be on the hoops. Others do not 
take the cheese from the hoops to dress them, but 
place a starched cap-cloth in the hoop before adding 
the curd. Then, in dressing, the bandage is pulled 
up from the top and, after being trimmed, a starched 
cloth is placed on the upper end. This method 
causes a greater waste of bandage, but otherwise 
is satisfactory. The mechanical manipulations in- 
volved in preparing the hoops and dressing the 
cheese can be properly learned only from actual 
practice. 



44 SCIENCE AND PRACTICE OF CHEESE-MAKING 

SIZES OR STYLES OF AMERICAN CHED- 
DAR CHEESE 

American cheddar cheese has come to be put upon 
the market in an increasing number of varieties or 
styles in respect to size. The main difference in 
most cases is simply one of shape or size. The fol- 
lowing list includes the most common varieties that 
appear in trade : 



Name 



1. Cheddar or Export 

2. Flats or twins 

3. Home-trade 

4. Daisies 

5. Young America 

6. Longhorn 

7. Picnic 

8. Square 

9. Print 



Shape 



Approximate 
Size 



Cylindrical 



Rectangular 



In. diam. 
14-15 
14-15 
11-13 
12-13 
7-8 
5 

4-5 
Various sizes 
lOx lOx 2f 



Approximate 
Weight 



Pounds 
60-70 
30-35 
20-25 
20 

8-12 
12 
1-2 

(3-4 in. thick) 

10 (marked in blocks 
or prints) 



CHAPTER V 

Moisture and Acidity in Curd and Cheese : 
Conditions, Effects and Control 

The detailed operations of cheese-making have 
for their primary object, in large measure, regula- 
tion of the amount of water and degree of acidity 
in the curd. So important is the control of these 
factors in relation to the quality of cheese, that 
sometimes, under abnormal conditions, as, for ex- 
ample, in case of ove-rripe milk, they can be regu- 
lated only by sacrifice of some of the fat, and the 
question of saving fat then becomes a matter of 
secondary importance. Of such importance is a 
knowledge of these factors and their relations to the 
detailed operations of cheese-making that a special 
chapter seems desirable, even though the treatment 
involves some repetitions. 

To a considerable extent, moisture and acidity 
are closely associated. Water means whey, of 
course, and the most important constituent of whey 
is milk-sugar, the raw material used in making 
lactic acid. The larger the percentage of water 
or whey in curd or fresh cheese, the larger is the 
amount of milk-sugar, and, therefore, the greater is 
the degree of acidity that can be developed. The 
relations of moisture can be better understood if 
we keep in mind the connection between (i) 
moisture, (2) whey, (3) milk-sugar and (4) acidity. 

45 



46 SCIENCE AND PRACTICE OF CHEESE-MAKING 

CAUSES OF EXCESSIVE MOISTURE 

Amon^ the most common causes of excessive 
water in curd and cheese are the following: (i) 
Cutting curd coarse or when too hard; (2) insuffi- 
cient heating of curd in whey; (3) heating too 
rapidly, thus hardening the outside of the pieces 
of curd and preventing escape of whey; (4) low 
degree of acidity before removing whey, usually 
associated with, or caused by, insufficient heating; 

(5) allowing curd to lie in whey too long and re- 
absorb whey; (6) insufficient stirring of curd after 
removal or partial removal of whey; (7) high 
pilings of curd; (8) prolonged maturing in cheddar- 
ing operation and postponement of milling in case 
of soft curd; (9) insufficient amount of salt; (10) 
soaking curd in water previous to salting (p. 57). 

CAUSES OF INSUFFICIENT MOISTURE 

The following are common causes of insufficient 
moisture in curd: (i) Cutting curd very fine; (2) 
heating curd too long or at too high a tempera- 
ture; (3) excessive stirring of curd when the whey 
is removed; (4) too much salt; (5) excessive loss 
of fat may cause curd or cheese to appear too dry; 

(6) high temperature and low humidity in curing- 
room. 

EFFECTS OF EXCESSIVE AND OF DEFI- 
CIENT MOISTURE 

Among the more prominent effects to be noticed 
in relation to water in cheese-curd and cheese, we 



MOISTURE AND ACIDITY IN CURD, ETC. 47 

mention the following: (i) Development of acid- 
ity; (2) influence on body; (S3) relation to texture, 
(4) effect on flavor; (5) influence on keeping qual- 
ity; and (6) relation to finish. 

Moisture and acidity. — The introduction to this 
chapter gives the cause for the close relation of 
moisture in curd to the formation of acid. In 
case of a zvet curd, characterized by much water 
(whey), we have a greater amount of milk-sugar 
ready to form an additional amount of acid ; and, if 
the temperature and other conditions are favor- 
able, acidity increases rapidly. In the case of a 
dry curd, the acidity increases more slowly, because 
there is less whey, which means less milk-sugar with 
which to make acid. 

Moisture and body. — Curd containing too much 
moisture (whey) becomes soft and produces a soft, 
weak-bodied cheese (p. 87), which in extreme 
cases is sticky and pasty (p. 63). The soaking of 
curds in water after milling causes the absorption 
of 5 per cent of water, more or less, and usually 
results in a poor body. Cheese containing too little 
moisture becomes dry, mealy, crumbly, more or 
less rubbery, tough and hard. Such cheese is in 
no way attractive. When curd is too dry, the 
maturing process takes place with some degree 
of difficulty and the curd is slow to change into 
the characteristic, mellow, smooth, meaty body that 
is desired. This is due to the presence of too little 
whey in the curd; that is, too little milk-sugar with 
which to form acid. 

Moisture and texture. — Excessive whey In curd 
and cheese Is apt to favor the production of holes, 



48 SCIENCE AND PRACTICE OF CHEESE-MAKING 

especially when exposed to high temperatures. 
Under the combined conditions of such defects of 
texture and the soft, pasty body characteristic of 
such cheese, the cheese easily loses its shape, bul- 
ging more or less ; this sometimes goes so far as to 
cause the cheese to roll off the shelf. 

Moisture and flavor. — Cheese made from curd 
containing a large percentage of water (whey) is 
apt to develop offensive flavors in ripening, espe- 
cially when kept at temperatures above 65° F. In 
some cases, excessive moisture results in sour or 
acid cheese. Dry cheese develops flavor slowly 
and can stand a higher ripening temperature. 

Moisture and keeping quality. — Cheese contain- 
ing a large amount of moisture has poor keeping 
quality, as already indicated above in connection with 
flavor and texture, while the reverse is true of 
dry cheese. 

Moisture and finish. — Cheese containing too 
much moisture loses its shape easily in hot 
weather, when the temperature of the curing- 
room can not be controlled. In such cheese, the 
rind formation is usually poor and cap-cloths do not 
stick well. 

CONTROL OF MOISTURE IN CHEESE- 
MAKING 

We now give briefly the means to be used in 
controlling moisture at different stages of cheese- 
making, 

(i) Cutting curd. — The finer the pieces into 
which the curd is cut, the more easily does the 



MOISTURE AND ACIDITY IN CURD, ETC. 49 

whey escape ; the larger the pieces of curd, the 
Ic^s rapid the escape of whey. Under the same 
conditions of treatment, a coarse-cut curd retains 
more whey than one fine-cut. When curd is cut 
before it becomes hard the whey escapes more 
easily than in the case of curd cut after it becomes 
hard. 

(2) Heating curd in whey. — When the tem- 
perature of curd in whey is raised too rapidly, the 
film on the outside of the pieces of curd is harder 
and more impervious, which seriously interferes 
with the escape of whey. If the temperature is 
not raised sufficiently high, the whey does not 
escape as completely as it should; this is especially 
the case when an insufficient degree of acidity is 
developed. Therefore the curd in the whey should 
be heated gradually (p. 30) and the temperature 
raised to the degree called for by the existing con- 
ditions (p. 29). For method of avoiding dry curd 
see p. 121. 

(3) Removal of whey. — The whey should be 
removed promptly when the curd is properly firmed. 
When allowed to lie in whey after reaching the 
right condition, the curd may reabsorb whey, which 
can be removed only with extreme difficulty and 
usually with considerable loss of fat. 

(4) Stirring of curd. — Curd should be freed from 
whey and made properly dry by sufficient stirring 
after removal of whey (p. 32). 

(5) Cheddaring curd. — In case of wet curd, it 
should not be piled too high in the operation of 
cheddaring, since this results in retention of more 
whey than when curd is cut fine and not piled 



50 SCIENCE AND PRACTICE OF CHEESE-MAKING 

at all. In the case of dry curds, pile higher, etc., 
(p. I2l). ^ 

(6) Milling curd. — Early milling of curd favors 
the escape of whey and may be resorted to when 
too much whey is present at this stage, especially 
in the case of a soft curd. Dry curds should not be 
milled early. 

(7) Salting curd. — The amount of whey in 
cheese can be controlled, to some extent, by the 
amount of salt used. In case of excessive moisture 
in curd at the time of salting, this may be reduced 
by using an increased amount of salt. In case of a 
dry curd, less salt should be used (p. 121). 

(8) Ripening process. — The amount of mois- 
ture in cheese can be regulated to a considerable 
extent by control of temperature and humidity in 
the curing-room (p. 317). Covering cheese with a 
layer of paraffin goes far in retaining water in cheese 

(p. 319). 

CAUSES OF EXCESSIVE ACIDITY 

Among the common causes of excessive acidity 
in curd and cheese are the following : ( i ) Taking 
too much overripe milk from patrons; (2) ripen- 
ing milk too much in vat before adding rennet ; 
(3) use of too much starter; (4) too long contact 
of curd with whey or too high temperature; (5) 
any condition which favors the retention of too much 
whey in curd and cheese (p. 116). 

CAUSES OF INSUFFICIENT ACIDITY 

The following are common causes of too low a 
degree of acidity: (i) Insufficient ripening of 



MOISTURE AND ACIDITY IN CURD, ETC. 5 1 

milk before adding rennet; (2) low degree of tem- 
perature in heating curd in whey; (3) removal of 
whey too soon; (4) any condition that favors the 
rapid removal of whey and the formation of an 
excessively dry curd (p. 121). 

EFFECTS OF EXCESSIVE AND DEFICIENT 

ACIDITY 

Among the more prominent effects to be no- 
ticed in relation to acidity in curd and cheese, we 
mention the following: (i) Influence on rennet 
action; (2) relation to shrinking of curd; (3) ef- 
fect on expulsion of whey; (4) influence on color 
of cheese; (5) relation to body of cheese; (6) ef- 
fect on texture of cheese; (7) influence on flavor 
of cheese; (8) relation to keeping quality of 
cheese; and (9) effect on finish or general appear- 
ance. 

Acidity and rennet action. — At the temperature 
used in cheese-making, rennet-extract coagulates 
milk-casein only when acids or acid salts are pres- 
ent (p. 306). The greater the percentage of acidity, 
up to certain limits, the more rapid is rennet 
coagulation, other conditions being uniform (p. 

307)- 

Acidity and contraction of curd. — The greater 
the acidity of milk, the more rapid is the contrac- 
tion of the curd, other conditions being uniform. 
This is not the same as saying that the contraction 
is caused by acidity; acidity is probably one of two 
or more causes, or it may be simply a necessary 
condition for the continued action of rennet, tem- 
perature being another important condition for the 



52 SCIENCE AND PRACTICE OF CHEESE-MAKING 

shrinking of curd. The knowledge of the relation 
of acidity and temperature to contraction of curd 
enables the cheese-maker to heat the curd in the 
whey more rapidly, since, in the case of excessive 
acidity at the start, he can increase with comparative 
rapidity the temperature, without danger of harden- 
ing the external film of the small pieces of curd and 
so preventing further expulsion of whey. 

Acidity and expulsion of whey. — The contrac- 
tion of curd is closely associated with expulsion of 
whey and the relation of acidity to the two actions 
is practically the same. 

Acidity and color of cheese. — Formation of too 
great a degree of acidity bleaches the color in the 
curd, making it pale when the action is even, and 
mottled when the acidity is different in different 
portions. This condition is generally caused by the 
retention of too much milk-sugar (whey) in curd 
and cheese. 

Acidity and body of cheese. — Excessive acidity 
produces imperfect body in cheese, making it 
harsh, corky and mealy. A certain degree of acidity 
is an essential condition, if not one of the causes, 
of the formation of a smooth, firm, silky body. 
Insufficient acidity may cause cheese to be weak- 
bodied. 

Acidity and texture. — Cheese made from curd 
containing a small amount of acidity is often faulty 
in texture. Among such defects are holes, usually 
called *'sweet holes." Excessive acidity and cracks in 
cheese are often associated. 

Acidity and flavor. — The characteristic flavor of 
cheddar cheese is not developed without a certain 



MOISTURE AND ACIDITY IN CURD, ETC. 53 

degree of acidity. Excessive acidity (whey) gives 
the cheese a sour flavor. Insufficient acidity is apt 
to be accompanied by a sickish flavor, unless the 
cheese is ripened with care at sufficiently low tem- 
perature. 

Acidity and keeping quality. — It has been al- 
ready stated (p. i8) that the presence of lactic 
acid bacteria in milk and curd is essential to pre- 
vent the development of undesirable forms of 
fermentation, which may be present in the early 
stages of cheese-making. The lactic acid thus 
formed is the active material employed in doing this 
sanitary work. Cheese with too little acidity usually 
becomes defective in flavor in a comparatively short 
time. 

Acidity and finish. — Excessive acidity (whey) 
causes formation of poor rind ; frequently the rind 
cracks and leaks whey. 

CONTROL OF ACIDITY IN CHEESE- 
MAKING 

Below we give in brief form the means to be used 
in controlling acidity in the operations of cheese- 
making. 

(i) Producer's care of milk. — In order to re- 
tard the too rapid growth of lactic acid bacteria 
before milk is delivered at the cheese-factory, the 
milk should be cooled at once after milking to 60° 
F., or better to 50° F., and not allowed to get above 
this temperature. 

(2) Ripening milk. — In making sweet-curd 
cheese, care must be taken not to ripen the milk 



54 SCIENCE AND PRACTICE OF CHEESE-MAKING 

too much^ a mistake too often made by cheese- 
makers. Milk which is overripe, whether at the 
time of dehvery or as the result of ripening after 
delivery, is difficult to handle (p. 122). In the 
methods often employed, much loss of fat is often 
experienced in order not to sacrifice quality in cheese. 
The use of commercial starters (p. 19) gives the most 
rehable results in ripening milk. 

(3) Control of whey. — The degree of acidity in 
curd and cheese is primarily dependent upon the 
amount of whey retained, and control of the amount 
of whey really means control of acidity. The methods 
for this have been given (p. 54). 

(4) Amount of acid at different stages. — The 
degree of acidity should be kept under careful con- 
trol at each stage of the operations of cheese- 
making, which is done by careful regulation of 
temperature and the different prescribed manip- 
ulations of the curd. There must be a careful ad- 
justment of conditions in respect to (i) the 
rapidity of formation and thickening of the film 
around the pieces of curd, (2) the contraction of 
the curd, (3) the expulsion of whey, and (4) the 
degree of acidity. 



CHAPTER VI 

Modifications of Cheddar Process and 
Miscellaneous Subjects 

In describing and discussing in detail the various 
operations involved in making American cheddar 
cheese, it has seemed best to reserve for a special 
chapter several subjects which are more or less 
closely related to this method of cheese-making, 
but which do not form an essential part of it. Of 
the many topics which might come in this chapter, 
the following have been selected for consideration : 
(i) "Stirred-curd" method; (2) "soaked-curd'' 
method; (3) pasteurized milk in cheese-making; 
(4) slow-ripening and quick-ripening cheese; (5) 
home-trade cheese; (6) use of artificial acids in 
cheddar cheese-making; (7) the use of pepsin in 
cheddar cheese-making; (8) whey butter; (9) dis- 
tribution and value of whey; (10) cheese poison; 
(11) starters in relation to yield of cheese; (12) 
making butter and cheese. 

THE ^^STIRRED-CURD" OR "GRANULAR" 
PROCESS OF CHEESE-MAKING 

This process was exclusively used in America 
for many years and is still in operation in some 
cheese-factories. While it is not our purpose to 
present a detailed description of this method, it is 
desirable, as a matter of information, to state its 

55 



56 SCIENCE AND PRACTICE OF CHEESE-MAKING 

most essential points, especially those in which it 
differs from the cheddar method. The cheddar and 
stirred-curd methods are identical until the time 
comes for the removal of the whey from the curd, 
when they differ in the following respects : ( i ) In 
the cheddar process the whey is removed from the 
curd when the hot-iron test shows strings yi to yi 
inch long; in the stirred-curd process, the curd re- 
mains longer in the whey, until the hot-iron test 
shows strings 5^ to i inch long. (2) After the re- 
moval of whey, the curd, in the cheddar process, is 
packed and then cheddared; while, in the stirred- 
curd process, the curd is transferred to a curd-sink 
and is more or less frequently stirred, so that the 
small pieces are kept separate; and at no time is 
the curd permitted to pack in a solid mass. The 
main object of keeping the curd longer in the whey 
is to firm the curd to such an extent that it can be 
kept in the ''granular" form more easily. (3) In the 
cheddar process, the time between the removal of 
whey and salting is much longer than in the stirred- 
curd method; while (4) the time between salting 
and pressing curd is much longer in the stirred- 
curd process. These general differences are well 



Method used 


Time from reach- 
ing 98° F. to re- 
moving whey 
from curd 


Time from remov- 
ing whey to salt- 
ing curd 


Time from salting 

to pressing 

curd 


Cheddar 

Stirred-curd 

Cheddar 

Stirred-curd .... 

Cheddar 

Stirred-curd .... 


Minutes 

90 
175 

62 
100 

90 
164 


Minutes 
200 

25 
133 

15 
230 

25 


Minutes 
30 
95 
10 
100 
30 
140 



MISCELLANEOUS SUBJECTS 57 

illustrated by the foregoing data, which were ob- 
tained at the New York experiment station in mak- 
ing different portions of the same milk into cheese 
by these two methods. 

It will be noticed that, in general, the total amount 
of time consumed is about the same by either 
method. The time is simply distributed differently 
at certain stages of the work. 

It is much more difficult with this method to 
make cheese of perfect texture, at least considered 
from the standpoint of the type of cheese intended 
for export. It was ^ the influence of the demands 
of the English market which caused American 
cheese-makers to change from the stirred-curd to 
the cheddar method. The cheddar process has the 
marked advantage of enabling the cheese-maker 
to control his operations more completely and pro- 
duce cheese of close texture. Greater skill is re- 
quired to produce results by the stirred-curd method 
equal to those obtained with the cheddar method. 
Under ordinary conditions, the stirred-curd method 
produces cheese with a little higher content of mois- 
ture, but not necessarily so. The loss of fat is the 
same by either method. 

THE "SOAKED-CURD" METHOD 

This is a modification of the cheddar method, 
which has for its object an increase of water other 
than that derived from the whey. It is to be dis- 
tinguished from the advantageous practice of wash- 
ing curd in the case of abnormal flavor, excessive 
acidity, etc. It is applied to both skim-milk and 



58 SCIENCE AND PRACTICE OF CHEESE-MAKING 

normal-milk cheese. The process is simply this: 
When the curd has matured ready for salting, it is 
covered with cold water and allowed to soak 10 to 
15 minutes. In this way the amount of water in 
100 pounds of cheese can be increased ordinarily 
4 or 5 pounds, producing a cheese with 41 to 44 
per cent of water. The soaking of curd by this 




FIG. 9 

Showing the effect of excessive moisture in a soaked-curd cheese upon the 
body. The cheese with normal moisture keeps its shape perfectly. The soaked- 
curd cheese bulges at the sides and flattens down if kept at temperatures 65 or 70 
degrees F. 

process not only increases the yield of cheese by 
the incorporation of water other than what was a 
part of the original milk from which the cheese was 
made, but it also dissolves from the curd (i) milk- 
sugar; and (2) the soluble calcium salts, especially 
acid calcium phosphate. These normal cheese con- 
stituents, which are thus removed from the curd, 
are essential to the normal ripening process of the 



MISCELLANEOUS SUBJECTS 59 

cheese and, in their absence, cheese undergoes ab- 
normal fermentations as the result of the action of 
putrefactive bacteria. These facts have been es- 
tablished by work done at the Cornell University 
experiment station. This practice has been de- 
fended on the ground of removing undesirable "im- 
purities" carried into the cheese by the whey. This 
is a pure assumption which has no foundation in 




FIG. 10 

Showing the difference between the close texture of normal cheese and the 
loose, spongy texture of a soaked-curd cheese. 

fact. The whey-solids, thus miscalled ''impurities," 
are normal constituents of cheese and are necessary 
to the completion of the ripening process when 
present in normal amount. Cheese made by the 
soaked-curd process is very properly not permitted 
the use of the brand designed for whole-milk cheese 
in New York state, on the following grounds : ( i ) 
Water other than that present in the original milk 
from which the cheese was made is incorporated 
with the cheese for the purpose of increasing its 



6o sciii:NCi': and rRAcncii of ciieese-jmaking 

\vcii;ht vvithonl iiiiproviiiL;" its (jiialit\'; .-md (J) llu' 
soaking' process removes normal conslilnents tlial are 
essential to the ripening; of the cheese. 'These ^ronnds 
are l)ase(l n])on estal)lishe(l facts. 

Cheese prochiced hy the soaked-curd process 
usually exhihits llie defects characteristic of clieese 
conlainini;' an excessive anu)unt of moisture; these 
are weak hody and loose texture (pp. 8()-87). When 
kept at temperatures above 65° or 70° h\, such 
cheese fails to stand up like normal cheese and it 
also suffers in texture from the elTects of gassy fer- 
mentations, h'igs. 9 and 10 well illustrate the truth 
of these statements. They rei)resent work done at 
the Cornell iMiiversity ex])erimcnt station with 
cheese made according to the soaked-curd method. 

CHEDDAR CHEESE FROM PASTEURIZED 

MILK 

Many attem|)ls have heen made to manufacture 
cheddar cheese from pasteurized milk. The results 
in America have not heen wholly encouraging up to 
the present time. The cheese is generally im]KM-fect 
in body, lacking in llavor and slow in ripening. We 
do not, therefore, think it desirahle to devote fm*- 
ther attention to the various modifications of details 
re(|uire(l in its manufacture. It is said that nmch 
skim-milk cheese is successfully made in Denmark 
from ])asteuri/.cd milk. 

CONDITIONS OF CHEESE-MAKING 

PROCESS FOR QUICK-RIPENING 

AND SLOW-RIPENING CHEESE 

Certain conditions of tlie cheese-making proc^ss 
promote, while others retard, the rapidity of ripen- 



MISCI'.l.l.ANI'.OUS SlM'vjI'A'lH 6t ' 

iiii;". 'y\\c i;cMKMal rclalion oi tlirfcmil i-oiulitions (o 
the rai)i(l or slow rato ol clu'cso ripcMiiiii; may ho 
shown h)' the followiiiL; lonii ol" slaU'iiu'iil : 

Conditions that may C'oiulitions (hat may 

promote riponiii^': retard ripenini;: 

(i) increase ol ripening (i) Decrease ol ripen- 

temperature. inj;- lemperalnre. 

(2) l.arger amount of (2) Smaller amount of 

rennet. reiniel. 

(3) More moisture in (3) Less moisture in 

cheCvSC. cheese. 

(4) f.ess salt. (4) More salt. 

(5) Larj^e vsizc of (5) Small size of cheese. 

cheese. 
(()) Moderate amount of (C)) Deficient acidity or 
acid. excess ol acidity. 

if a cheese is desired that ri|)ens (|uickly, it 
should contain more than the nsnal amount ol ren- 
net, a moisture content of ahont .jo per cent or 
more, and ahout 1 to I'j pounds of salt lor i.ooo 
pounds of milk. Then it should he kept at a tem- 
l)eratnre hetween ()(>" l'\ and 70" l'\, if it is to he 
])laced ill the liands of consnmei-s in om- month or 
six weeks, and the atmosphere of the curin|;-room 
should have a humidity of 75 to S5 per cent ol 
saturation. I lowever, it should he statecl that 
cheese made to ripen <|uickly skives hetler results 
in commercial (juality when ripened at a lowei- 
temi)erature than ()o'' h\ and held a longer 
time. 

h'or a slow-ripenini^- cheese, not nioic than 2J/2 
ounces of rennet -c-.\tracl, such as llansen's, should 



62 SCIENCE AND PRACTICE OF CHEESE-MAKING 

be used for 1,000 pounds of milk, and about 2 to 2^ 
pounds of salt. The other conditions that influence 
the moisture content of cheese, such as the tem- 
perature of heating- the curd, the fineness of cutting 
curd, the amount of acid developed in the curd, 
cheddaring, etc. (p. 45), should be well under 
control, so as to produce a cheese containing, when 
fresh from the press, about '}^y per cent of water. For 
ripening, it should be kept at a temperature below 50° 
F. in a fairly moist atmosphere for a period of 3 to 6 
months or more. 

HOME-TRADE CHEESE 

The majority of cheese consumers desire a cheese 
soft in body and with a mild, clean flavor. Soft- 
ness is synonymous with richness in cheese to 
most people. While it is true that cheese rich in 
fat possesses a characteristic softness, it is not true 
that all soft cheese is rich in fat. The desire for a 
mild-flavored cheese is a reaction from the taste 
for a cheese of strong, pungent flavor. To meet in 
the easiest way the demand for soft-bodied, mild- 
flavored cheese, there has arisen quite an extensive 
manufacture of what is known as "home-trade" 
cheese. The method of making this kind of cheese 
varies in its details in different localities, but the 
general object is the production of a quick-curing 
cheese which will be ready for consumption in four 
to six weeks. The distinctive characteristics of 
such cheese are its high water content, a conse- 
quent softness of body and open texture, a mild 
flavor when a few weeks old, and a poor keeping- 
quality. These results are attained, in general, by 



MISCELLANEOUS SUBJECTS 63 

using large amounts of rennet-extract, developing 
less acidity, heating the curd in the whey to 103° 
to 110° F. and ripening at 60° to 70° F. In many 
cases, where the conditions of ripening are not un- 
der control, home-trade cheese is made only in the 
fall, since there is less risk in handling the ripening 
process at a time when the temperature is not high. 
Home-trade cheese, when green, usually contains 
38 to 40 per cent of water, but the percentage may 
run up to 43 or even 45. The fact that this soft 
cheese is more extensively made in the fall has led 
cheese-makers to believe that ''milk very rich in fat, 
such as strippers' milk, is liable to cause a pasty 
cheese." Such a belief could hardly be further from 
the truth, as shown by the facts given in Chapter 
XV, pp. 164-167, where the influence of advancing 
lactation on the composition of milk is discussed. 

It should be stated in this connection that, in New 
York state, a large proportion of the cheese made 
under the name of home-trade is of a type quite dif- 
ferent from that described above. In the process 
of making, the temperature is not allowed to go above 
98° F. and the percentage of moisture is kept at 7,8 
to 40. The resulting cheese is firm-bodied, close-tex- 
tured and of good-keeping quality. It is the best 
type of home-trade cheese and is in large demand. 

USE OF ARTIFICIAL ACIDS IN CHEDDAR 
CHEESE-MAKING 

Attempts have been made to use artificial lactic 
and other acids in making cheddar cheese, in order 
to hasten the cheese-making operations. Theoreti- 
cally, the addition of small amounts of dilute acid 



64 SCIENCE AND PRACTICE OF CHEESE-MAKING 

can take the place of starters in hastening the ac- 
tion of rennet, and, to some extent, in the subse- 
quent stages. While it is possible to assist the lactic 
acid bacteria in this way, great caution is required. 
The addition of too much acid results in the produc- 
tion of cheese that does not ripen. So far as we 
know, the application of artificial acids in cheddar 
cheese-making has never been worked out to such 
an extent that all details are under control. While 
cheese of good quality can be made in this way, there 
is probably no advantage, even when the process is 
under absolute control ; and, in the absence of such 
control, no one should ever attempt to employ such a 
method in practical work. 

USE OF PEPSIN IN CHEDDAR CHEESE- 
MAKING 

Commercial pepsin prepared from the stomachs 
of sheep has been successfully used in place of ren- 
net-extract in making cheddar cheese. The special 
pepsin most used in this way is a scale-pepsin 
known as 1-3000 strength. Five grams of this pep- 
sin equal the coagulating power of 3 ounces of 
Hansen's rennet-extract. The pepsin is dissolved 
in cold water for use. In using pepsin, one should 
make a solution and test it in comparison with ren- 
net-extract on the same milk. (Modern Methods 
of Testing Milk, etc., pp. 125-126.) Pepsin has the 
following advantages over rennet-extract: (i) It 
is more concentrated and, therefore, more conven- 
ient and less expensive to ship. (2) If kept dry, 
pepsin retains its strength indefinitely, while ren- 
net-extract does not. These advantages of pepsin 



MISCELLANEOUS SUBJECTS 65 

over rennet-extract do not, of course, apply to ren- 
net poicdcrs. The quality of cheese made by use of 
pepsin does not appear to be inferior to that made 
by the use of rennet. Commercial pepsin is probably 
more expensive to use than rennet-extract and is not 
uniform in strength. ^ 

MANUFACTURE OF WHEY-BUTTER 

The fat in whey can be readily removed, in large 
part, by means of a centrifugal separator, and the 
resulting cream can be made into butter in much 
the same manner as cream separated directly from 
milk. The butter thus made is apt to be somewhat 
softer than in case of normal butter ; the flavor is 
fair to good. From the whey produced in making 
10,000 pounds of milk into cheese under normal con- 
ditions, about 25 to 30 pounds of whey-butter can 
be made under favorable conditions. This yield is 
based upon an average loss of 0.3 pound of fat in 
whey for 100 pounds of milk (p. 189). The removal 
of milk-fat from whey does not greatly reduce its 
feeding value. 

The question of making whey-butter is largely a 
matter of cost of production. In the case of small 
cheese-factories, the yield of butter would not 
repay the labor. In larger factories, it would be- 
come, to some extent, a question of the amount 
of fat in the whey. In general, it may be said 
that the manufacture of whey-butter will be 
usually found profitable under the following con- 
ditions : 

( I ) When the daily average milk supply is not 
less than 10,000 pounds and the amount of fat in 



66 SCIENCE AND PRACTICE OF CHEESE-MAKING 

whey averages 0.25 pound or more for 100 pounds of 
milk. 

(2) When the average cost of making whey- 
butter can be kept sufficiently low. The usual cost 
is 3 to 4 cents a pound, including cost of fuel, labor, 
coloring-matter, salt, etc. "Among the conditions that 
favor economy of production are the following: (a) 
A building so located and constructed that gravity 
can be used to carry whey to and from the separator 
at minimum cost; (b) a cheap supply of pure ice 
and cold water; (c) the possession of a centrifugal 
separator and a butter-making equipment as a part 
of the factory plant; (d) reasonable cost of fuel and 
labor. 

(3) When a gooa quality of butter is made. 
This, of course, requires pasteurization of cream, the 
use of a good commercial starter, extreme cleanliness 
at every stage of the butter-making process and proper 
sanitary surroundings. 

In St. Lawrence County, New York, several fac- 
tories have fcwmed a combination for the successful 
manufacture of whey-butter. The separated cream is 
sent by each to a central butter-making station. When 
all conditions are favorable, a cheese-factory receiving 
10,000 pounds of milk a day on the average, could 
with profit install the equipment necessary for making 
whey-butter. 

DISTRIBUTION AND VALUE OF WHEY 

The theoretical yield of whey for 100 pounds of 
milk averages about 90 pounds, with a variation 
between 87 and 91.5 pounds, according to the yield 



MISCELLANEOUS SUBJECTS (yj 

of cheese for lOO pounds of milk. The theoretical 
yield is reduced by the losses in the cheese-making 
operations, due ( i ) to evaporation of water and 
(2) to mechanical losses. The yield of whey varies 
with the composition of the milk and, therefore, 
with the time of season and other conditions that 
affect the composition of milk (p. 204). In gen- 
eral, it is safe to say that the yield of whey is about 
%'^ pounds for 100 pounds of milk, taking the sea- 
son as a whole ; but this yield is considerably 
reduced by losses in handling. In allowing each 
patron to take the portion of whey coming to him, 
the usual amount is 80 to 85 pounds for 100 pounds 
of milk delivered. Where the whey is valued by 
every patron, it is essential that each one be as- 
signed his just portion; otherwise some will always 
take more than belongs to them. There are various 
satisfactory devices for controlling the amount of 
whey each patron can take. 

The chief value of whey to patrons is as material 
for feeding pigs and calves in connection with 
other foods. The feeding value of sweet whey 
may be conservatively placed at 8 to 10 cents for 
100 pounds. For the composition of whey, see 
p. 197. Whey sours rapidly and loses a consider- 
able amount of its milk-sugar under ordinary con- 
ditions. In order that its highest food value may 
be realized, it is essential that it should be pasteur- 
ized promptly and the whey-vat always kept in clean 
condition (p. 197). It is not practicable to sterilize 
whey, because the heat needed for sterilization 
coagulates the albumin. Whey that is decidedly 
sour often has an iniurious effect on the animals 



68 SCIENCE AND PRACTICE OF CHEESE-MAKING 

to which it is fed, especially when fed alone and 
in excess. There is another even more important 
reason why whey should be pasteurized. The 
whey-vat has been known to become a distributing 
source of disease among calves and pigs and of ab- 
normal fermentations that injure the quality of cheese. 
Sweet whey has a value of 6 or 7 cents per 100 pounds 
when sold for the manufacture of milk-sugar, but com- 
paratively little whey can be actually disposed of in 
this way. 

CHEESE POISON 

For a long time it was known that cheese some- 
times acts as a violent poison, but it was not until 
about 25 years ago that a specific poisonous com- 
pound was isolated from cheese. Many cases of 
cheese poisoning had occurred in Michigan at the 
time and the matter was investigated by Dr. V. C. 
Vaughan, professor of physiological chemistry at 
the University of Michigan, who succeeded in sepa- 
rating from some of the poisonous cheese an in- 
tensely poisonous compound, which he called tyro- 
toxicon (cheese poison). The poison is present in 
cheese in only very minute amounts, but is intensely 
powerful. A drop of a highly dilute solution of this 
poison placed on the tongue produces a characteristic 
benumbing sensation. This poison is the result of 
bacterial action and is produced only by those bacteria 
which are associated with conditions of filth. There 
are sometimes also other poisons in cheese, less well 
known. 



MISCELLANEOUS SUBJECTS 69 

STARTERS IN RELATION TO YIELD OF 

CHEESE 

When a cheese-maker uses comparatively large 
amounts of starter, as 5 pounds for 100 pounds of 
milk, the question arises as to whether this does 
not increase the yield of cheese and is not practi- 
cally equivalent to adding" the same amount of 
skim-milk. The amount of added casein thus intro- 
duced is about 2 ounces and is equivalent to an 
increased yield of cheese amounting to about 5 
ounces for 100 pounds of milk. Theoretically, the 
practice of adding large amounts of starter might 
lead to abuse ; but rennet-extract does not act upon 
the coagulated casein of sour milk or of buttermilk. 
The casein contained in the starter, although held 
fast in the coagulum at first, separates to a large 
extent during the cheese-making in the form of 
fine particles. When a large amount of starter is 
used, these small particles are very noticeable in 
the whey. The fact that the addition of a starter 
to milk does not increase the yield of cheese has 
been brought out by work done in the dairy de- 
partment at the Cornell University experiment 
station. 

MAKING BUTTER AND CHEESE 

The question is often raised as to whether or not 
it pays to remove a part of the fat from milk and 
make butter and part-skim cheese. As a rule, it 
does not pay, unless one sells the part-skim cheese 
for whole-milk cheese, and this is very difficult to 
do now under our pure-food laws. The best advice 



/O SCIENCE AND PRACTICE OF CHEESE-MAKING 

that can be given is to make either butter or cheese, 
but not to mix the manufacture of the two products. 
Some cheese-factories drop cheese-making in the 
fall and make butter during the winter. The rela- 
tive price of cheese and butter will determine which 
pays better. In general, it can be said that butter- 
making pays better than cheese-making whenever the 
price of butter is greater than two and one-third 
times the price of cheese per pound. For example, 
when cheese sells at lo cents a pound, butter-making 
will pay better, if the price of butter is above 23 1-3 
cents a pound. 



CHAPTER VII 

Care, Shipment and Sale of Cheese 

It has been said that a cheese is really only half 
made when it is taken from the press. This is, in a 
great measure, true, because the conditions of tem- 
perature and humidity to which a cheese is sub- 
jected during the process of ripening or curing 
largely determine its quality. An excellent cheese 
may be absolutely spoiled by unfavorable ripening 
conditions, while a cheese of inferior quality may 
be much improved by being kept under favorable 
conditions. The subject of cheese-ripening in its 
practical relations is discussed in Chapter XXVI, 
PP- 379-394. 

CLEANING THE SURFACE 

When each cheese is taken from the press, it should 
be wiped off with a dry cloth, and any rust-spots or 
finger-marks removed. Deep-seated spots of dirt can 
be more easily removed by the use of a brush and hot 
water. 

PLACING CHEESE IN CURING-ROOM 

No cheese should be placed in the curing-room 
until it is clean and well finished. A badly finished 
or dirty cheese never attracts a cheese buyer, in- 
spector or consumer. Imperfections in quality are 

71 



y2 SCIENCE AND PRACTICE OF CHEESE-MAKING 

often overlooked if the finish and general appearance 
are good. 

When cheese is placed in the cnring-room, it 
should be arranged in a neat manner upon clean 
shelves or tables. Too many cheese-makers allow 
the cheese-shelves to become moldy and dirty ; con- 
sequently, when a clean cheese is placed on them the 
end surfaces soon become stained and dirty. The 
shelves should be thoroughly cleaned after each ship- 
ment of cheese leaves the factory. 

TURNING CHEESE DURING RIPENING 

PROCESS 

Each cheese should be turned on the shelf every 
morning until ready for shipment. At the time of 
turning, if an excess of moisture or any mold is 
present, it should be wiped off with a dry cloth, or 
with a damp one wrung out of a lo per cent solution 
of formaldehyd. 

MARKING DATE OF MANUFACTURE 

When cheese is placed in the curing-room, the 
date of its manufacture should be stamped on each, 
so as to correspond with the number of the manufac- 
turing record of the same date and thus avoid errors 
in shipment. 

USE OF CHEESE BRANDS 

Many states have statutes providing for the 
branding of cheese. The brand usually indicates 
whether the cheese has been made ;.from whole 



CARE,, SHIPMENT AND SALE OF CHEESE 73 

milk or skimmed milk. Brass stencils for this pur- 
pose are usually sent to factories by the state de- 
partments of agriculture, which keep a record of 
the number of each factory, and this particular 
number appears as part of the brand. This is to 
protect the manufacturers of whole-milk cheese 
from dishonest competition with those who remove 
part or all of the fat from the milk before making 
it into cheese. In Canada many factories stamp 
the name of the factory on the cheese. In many 
instances, this is a good plan, if the quality of the 
cheese is good, but disastrous if the cheese is defec- 
tive in quality. 

WHEN CHEESE SHOULD BE SHIPPED 

The age at which cheese should be shipped from 
the factory depends on several conditions. If the 
curing-room is one in which the temperature and 
humidity cannot be controlled at all, the cheese 
should be shipped within a few days to some place 
where it can be kept under proper conditions. In 
some places, central cold storages are located 
where cheese, either before or after selling, is sent 
to ripen. If the temperature In the cheese-factory 
can be controlled, the cheese should not be shipped 
so soon. Cheese lo days old is young enough, and, 
if for export, two weeks will be much better. An 
export cheese is not very palatable in less than one 
month. A home-trade cheese containing a high 
percentage of moisture may be ready at an earlier 
date (p. 62) 

During the past few years, complaints, in increas- 
ing number, have been made by foreign cheese 



74 SCIENCE AND PRACTICE OF CHEESE-MAKING 

merchants, who say that cheese is shipped to them 
before it is old enough. The Canadian g-overn- 
ment has lately been making vigorous efforts to 
overcome this practice, which has become too com- 
mon. The important point to be kept in mind is 
that the cheese should be in an edible condition when 
it reaches the consumer. 




FIG. 11 — DAIRY STUDENTS WEIGHING, PARAFFINING AND BOXING 

CHEESE 



COVERING CHEESE WITH PARAFFIN 

Loss of moisture in cheese can be largely pre- 
vented by coating the cheese with a thin layer of 
paraffin, and this can be done without injuring the 
quality. The higher the temperature, the greater 
is the prevention of loss. Another distinct advantage 



CARE, SHIPMENT AND SALE OF CHEESE 75 

in using paraffin is that it prevents cheese becom- 
ing- moldy. The cheese is allowed to dry well on 
the surface and is then dipped for 8 to 15 seconds, 
according- to the size and temperature of the 
cheese, in melted paraffin at a temperature of, at 




FIG. 12 — APPARATUS FOR PARAFFINING CHEESE 



least, 220^ F. Care must be taken to keep the par- 
affin from acquiring a disagreeable odor as a result 
of overheating. Cheese should be dry enough in 
three to seven days to be ready for paraffining, but 
the time will depend, of course, on the amount of 
moisture in the cheese and in the curing-room. The 
application of paraffin at a high temperature gives 
a thin coating that adheres tenaciously and de- 
stroys mold formation. If the temperature is too 



yG SCIENCE AND PRACTICE OF CHEESE-MAKING 

low, the coating will be too thick and will crack or 
break away from the cheese more easily. About 
5 or 6 ounces of paraffin will cover an 8o-pound 
cheese, and the cost is about 2^ to 3 cents. Most 
retail merchants are now in favor of having cheese 
coated with paraffin ; but in England many of the 
large exporters are not in sympathy with the idea, 
although the number of the latter is gradually de- 
creasing. If cheese is exposed to high tempera- 
tures after the paraffin is applied, its beneficial effect 
will be lost. F'or this reason, the average factory 
cannot paraffin cheese, and it is usually done at 
central cold-storage places, to which the cheese is 
shipped. 

WEIGHING CHEESE FOR SHIPMENT 

Before cheese is shipped, each one should be 
carefully weighed and the weights copied in dupli- 
cate. Special cheese-shipping books are available 
for this purpose. One copy is forwarded to the 
purchaser of the cheese and the other is kept at 
the cheese-factory. In most states, the cheese is sold 
according to the exact weight of each ''balanced 
beam." In Canada the factorymen are forced to 
allow the buyers "up-beam," plus ^ pound. This 
means that, for every cheese sold, the factoryman 
gives away at least Yx pound. In many cases it is 
more, because it is difficult for the cheese-maker to 
have the cheese always weigh so near the pound mark. 
Unfortunately, this has become an almost uncriticised 
practice and it is hoped that cheese-makers in 
Canada will soon awaken to a better method of selling 
cheese. 



CARE^ SHIPMENT AND SALE OF CHEESE 7/ 

BOXING CHEESE FOR SHIPMENT 

After cheese is weighed, each is placed in a box 
for shipment. A thin scale-board should be placed 
between the cheese and each end of the box to 
prevent the cheese sticking to the box. The box 
should fit the cheese closely and should be strong 
enough to stand shipment without breaking. If 
the box is too high, it should be pared down with 
a draw-knife. The lid of the box should just press 
lightly on the top of the cheese. Some shipping 
companies demand that the lids be securely fastened 
on every box. If the lids fit snugly, they will 
not come ofif easily in handling; but if nails are 
used, they should not be so long as to penetrate the 
cheese. 

STENCILING THE BOXES 

The weight of the cheese should be neatly 
stenciled on the side of the box in large figures 
and, if the cheese is for export, the name of the 
factory should also be stenciled on the side. It is 
bad practice to mark the weights with a lead 
pencil. Such marks do not look well and are often 
very indistinct, since all cheese-makers cannot 
make neat, plain figures. A rubber stamp is, per- 
haps, the quickest and neatest way. If a brass 
stencil is used, a mixture of coal-oil and lamp- 
black makes a very suitable blacking. Shoe-black- 
ing should not be used, because it easily becomes 
smeared and then makes the package appear un- 
tidy. 



78 



SCIENCE AND PRACTICE OF CHEESE-MAKING 



DRAWING CHEESE TO SHIPPING POINT 

Most cheese-factories are located in country 
places some distance from railway and steamboat 
facilities. The cheese is usually drawn to ship- 
ping- places by patrons of the factory. In many 
instances the wagons used are not fit for carrying 
cheese, and the boxes that were clean and neat 
become dirty or broken by the time they reach the 





FIG. 13 — A CHEESE-BOX, AS IT SHOULD .APPEAR 
WHEN READY FOR SHIPMENT 

station. The cheese should be drawn in clean, 
spring wagons and should be placed so that the boxes 
do not roll around and break. Clean straw placed 
on the bottom of the wagon-box improves the con- 
ditions of transportation. A covering of oiled canvas 
placed over the load of boxes will protect them from 
dust, rain and the heat of the sun. 



HOW TO SELL CHEESE 

When cheese-factories were first operated, the 
cheese was purchased by buyers, who visited the 



CARE, SHIPMENT AND SALE OF CHEESE 79 

factories and bought the cheese on its merits. Now- 
most cheese is sold on the dairy boards of trade. 
Large dealers send representatives to each cheese 
board with instructions to buy cheese at a certain 
price. Usually there is enough competition be- 
tween buyers to insure the full market prices. 
Buyers are allowed by their employer one-six- 
teenth to one-eighth cent per pound for buying 
cheese, and very often, in the heat of competition, 
they pay the cheese seller this commission in order 
to secure the cheese. This is not objectionable, 
if it does not continue too long. If the buyer re- 
ceives no pay for his work, he frequently finds fault 
with or rejects the cheese and asks for a reclaim of 
a few dollars from the cheese-maker, when other- 
wise the cheese would pass inspection. In sections 
where cheese is inspected in the factories, the cheese- 
board method is fairly satisfactory, but when the 
cheese has to be sent to a distant center of inspec- 
tion, there is continual complaining by either buyer 
or seller. 

METHOD OF PAYING FOR CHEESE 

With few exceptions, cheese is now shipped to 
the order of some bank. After the buyer has in- 
spected and accepted the cheese, he gives the seller 
a draft of his firm on the local bank for the value 
of the cheese. The bank then draws on the firm 
and the cheese belongs to the bank till the draft 
is hbnored. This method is a real cash business 
and protects the factoryman from losses caused by 
fraudulent practices of dishonest cheese merchants. 



CHAPTER VIII 

Commercial Qualities of Cheddar Cheese 
and Methods of Judging 

In commercial transactions in cheese, certain 
points or qualities have been adopted as a basis 
or standard in judging the commercial value of this 
product. The terms used in expressing the different 
qualities vary considerably in different market cen- 
ters, and the same expression is used with different 
meanings by different persons. Frequently indi- 
viduals use terms that are strictly local or per- 
sonal. It is desirable that there should be a 
uniform usage and a common understanding in re- 
spect to the terms used in judging cheese. The 
attempt is made here to discuss the terms in com- 
mon use and to define them as well as may be, in 
the hope that it may serve as an aid in bringing 
about a general agreement in respect to the use 
and understanding of the expressions employed 
in judging and scoring cheese. The definitions 
here given can hardly be expected to be in full agree- 
ment with the usage of everyone, since individuals 
differ from one another so much in their use of these 
terms. 

SAMPLING AND TESTING CHEESE 

In testing its commercial qualities, a sample of 
the cheese to be examined is obtained by means 

80 



JUDGING COMMERCIAL QUALITIES 8l 

of a cheese-trier. This is inserted nearly its whole 
length, if possible, into the cheese, turned around 
once and then drawn out, bringing with it, as the 
sample, a long, round cylinder, commonly called 
"plug." 

The plug should always be drawn from the top 
and not from the side, in order to avoid injuring the 
protective power of the bandage. The plug drawn 
is examined by smelling, feeling, appearance, etc., 
in reference to the various qualities mentioned 
below. 

TERMS USED IN DESCRIBING QUALITIES 
OF CHEESE 

The following qualities have been selected to serve 
as a basis in the commercial testing and scoring of 
cheese: (i) Flavor, (2) texture, (3) body, (4) color, 
(5) salt, and (6) appearance. 

Flavor. — By flavor is meant the quality that is 
perceptible to the smell and taste. The sense of 
smell is depended upon in testing flavor in cheese 
much more -largely than is the sense of taste, because, 
in examining a large number of samples of cheese 
in succession, constant tasting soon dulls not only 
the sense of taste but also that of smell. Flavor in 
cheese is due to the formation of some unknown 
compound or compounds during the ripening process 

(p. 375)- 

Testing flavor in cheese. — The flavor is best ob- 
tained by direct smelling of the plug as soon as it is 
drawn and, in addition, by crushing and warming 
some of the cheese between the thumb and fingers 
and then smelling. 



82 SCIENCE AND PRACTICE OF CHEESE-MAKING 

Terms used in describing cheese flavor. — From 
a great variety of names applied to various flavors 
found in cheese, the following terms are selected 
for consideration: (i) Perfect, (2) high or quick, 
(3) clean, (4) low or flat, (5) strong, (6) too 
much acid, (7) too little acid, (8) sour, (9) sweet 
or fruity, (10) rancid, (11) tallowy, (12) tainted, 
(13) stable, (14) weedy, (15) bitter, (16) cowy, 
(17) fishy, (18) hydrogen sulphid. 

(i) Perfect flavor applies to cheese when it some- 
what resembles that of first-class butter wnth an added 
quality of its own that is characteristic but cannot be 
described further than to call it cheese-like. It is 
sometimes described as "nutty." This flavor should 
be marked, but not strong. It should be free from 
all other flavors, particularly the more or less offen- 
sive products of undesirable fermentations. The taste 
should be mild and somewhat lasting, but should not 
be so sharp as to "bite" the tongue. 

(2) High or quick flavor is a delicate flavor that 
disappears quickly. 

(3) Clean flavor is free from every trace of un- 
pleasant aroma or taste. 

(4) Low or Hat flavor applies to slight traces, or 
absence, of flavor; it is insipid. 

(5) Strong flavor is a good flavor very pronounced 
but free from everything offensive ; it is a good flavor 
strongly developed. 

(6) Too much acid applies to flavor that smells 
somewhat sour, but does not taste sour. 

(7) Too little acid applies to a mild flavor, lacking 
jn character. 



JUDGING COMMERCIAL QUALITIES 83 

(8) Sour flavor is characterized by a sour taste 
when the cheese is fresh, owing to the presence of 
too much whey. 

(9) Szveet or fruity flavor is suggestive of artificial 
pineapple odor and is somewhat ''sickish" to taste. 

(10) Rancid flavor is that of butyric acid, more 
common in old cheese than in young. When very 
strong, it affects a delicate throat with a slight sensa- 
tion of choking or strangling. 

(11) Tallowy flavor is like that of tallow. 

(12) Tainted flavor includes a variety of odors, 
mildly to strongly offensive. 

(13) Stable flavor suggests the smell of cow ma- 
nure. 

(14) Weedy flavor applies to such abnormal 
flavors as come from onions, leeks, cabbages, rag- 
weed, etc. 

(15) Bitter flavor is self-descriptive. It is often 
due to certain fermentations that develop when a 
cheese is undersalted. 

(16) Coivy flavor is suggestive of the breath of a 
cow and may develop in cheese from some form of a 
fermentation. 

(17) Fishy flavor is self-descriptive. It is caused 
by certain ferments that are present in milk. 

(18) Hydrogen sulphid is a gas which gives the 
odor that is characteristic of the water of sulphur- 
springs. It is found in cheese ripened at high tem- 
perature. The odor is rarely, if ever, as strong as in 
the water of a sulphur-spring. A cheese with this 
flavor, or a fishy flavor, is technically known as a 
"stinker." The presence of this gas can be detected 
by holding a bright silver coin against the cheese-plug 



84 SCIENCE AND PRACTICE OF CHEESE-MAKING 




FIG. 14 — CHARACTERISTIC AP- 
PEARANCE OF A CLOSE-TEX- 
TURED CHEESE 



for a moment; the sil- 
ver tarnishes if any ap- 
preciable amount of 
hydrogen sulphid is 
present. 

Texture. — Texture, 
as applied to cheese, 
refers chiefly to com- 
pactness or appearance 
of solidity. It is quite 
common, unfortunate- 
ly, to regard the 









"body" as a part of 
the texture, but the 
two qualities are 
clearly distinct and 
should not be con- 
fused. 

Testing texture in 
cheese. — The texture 
of cheese is tested 
by an examination .pf 
the plug with refer- 
ence to the presence fig. 15 — characteristic appear- 
of holes The dIu^" ' ance of a loose or porous 

, , * . , texture 

is broken m two and' 

the broken ends 
examined for the 
characte ristic 
flinty appearance. 

Terms describ- 
ing t e X t u r e. — 

FIG. 16-typical texture of sweet- ^^'^ following 
CURD cheese terms are among 




JUDGING COMMERCIAL QUALITIES 



85 



those most commonly used in describing texture : 
(i) Perfect, (2) close, (3) loose, (4) mechanical- 
holes, (5) gas or pin-holes, (6) Swiss-holes. 





FIG. 17 — EFFECTS OF GASSY FERMENTATION IN CHEESE 

(i) Perfect texture in cheese is shown when a 
plug or a cut surface of the inside of the cheese 
presents to the eye a solid, compact, continuous 
appearance, free from breaks, holes and chunks. 




FIG. 18 — MECHANICAL-HOLES IN CHEESE NOT PERFECTLY 

CEMENTED 



86 SCIENCE AND PRACTICE OF CHEESE-MAKING 

When a plug is broken in two, it should show a flaky 
appearance, termed a "flinty" break, resembling the 
surface of broken flint or steel. 

(2) Close texture describes the appearance of a 
cut surface of cheese when free from all kinds of holes. 
Such cheese is often described as ''close-boring." 
(Fig. 14.) 

(3) Loose or porous texture is indicated by lack 
of solid compactness, being more or less full of 

holes, which vary from 
W^ a few (Figs. 15 and 16) 
J to enough to make a 
j spongy (Fig. 17) ap- 
i pearance. One variety 
, I is known as fish-eye, 
I due to action of yeasts 
^ (p. 126). 

(4) Mechanical-holes 
in cheese are irregu- 
lar, open spaces, 

FIG. 19— SWISS-HOLES caused by the incom- 

plete cementing of the 
pieces of curd in the press. (Fig. 18.) 

(5) Gas-holes or pin-holes are small holes, pro- 
duced by gaseous products of fermentation. 

(6) Swiss-holes are fairly large, round holes, such 
as are present in Emmenthaler cheese. (Fig. 19.) 

Body. — This term, used in connection with cheese, 
refers to the consistency, firmness or substance of 
cheese. It is largely influenced by the amount of fat 
and moisture in cheese. 





JUDGING COMMERCIAL QUALITIES S/ 

Testing body. — This quality is found by pressing 
a piece of cheese between the thumb and fingers. 

Terms describing body. — The following terms are 
among those used in describing the body of cheese : 
(i) Perfect, (2) solid or firm, (3) smooth, (4) silky, 
(5) waxy, (6) pasty or salvy, (7) stiff, corky or 
curdy, (8) weak-bodied, (9) mealy, (10) gritty, (11) 
watery, (12) overdry. 

(i) Perfect body in cheese is indicated when it 
feels solid^ firm and smooth in its consistency or 
substance. It does not crumble under pressure. A 
plug drawn from a cheese of perfect body should 
be smooth in appearance and not *'fuzzy." 

(2) Solid, firm or meaty body is indicated when 
cheese oflfers a certain amount of resistance under 
pressure, somewhat like that shown by a piece of fat 
pork or cold butter. The term meaty is also used. 

(3) Smooth-ho^iQd cheese, when pressed between 
the thumb and fingers, feels smooth and velvet-like, 
as distinct from harsh, gritty or mealy. 

(4) Silky-hodi^d cheese is smooth in feeling but 
not oversolid in consistency. 

(5) Waxy-ho^\td cheese is much the same as 
silky, but possessing more firmness or solidity. 

(6) Pasty or salvy cheese is very soft, usually 
from an excess of moisture. When pressed, it sticks 
to the fingers. 

(7) Stiff, corky or curdy cheese is hard, tough, 
overfirm ; it does not crush down readily when pressed 
in the hand. 

(8) J^^a^-bodied cheese is very soft, lacking in 
firmness, but not necessarily sticky like pasty 
cheese. 



88 SCIENCE AND PRACTICE OF CHEESE-MAKING 

(9) Mealy or crumbly cheese breaks down in fine 
crumbs when pressed. 

(10) G"n7^3;-bodied cheese feels harsh and gritty 
under pressure. 

(11) IVatery-hodied cheese is excessively soft, 
pasty and sticky. 

(12) In an overdry cheese the body is very hard 
or mealy. 

Color. — The color of cheese varies considerably, 
whether artificially colored or not. There appears 
to be an increasing- demand for uncolored cheese. 
The coloring varies from a pale yellow to a red- 
dish yellow, according to the demands of special 
markets. 

Testing color. — The color is tested by inspection 
with the eye, the examiner noticing particularly 
unevenness and any extreme condition of color. 

Terms describing color. — Color in cheese is de- 
scribed in the following terms: (i) Perfect, (2) 
straight, (3) translucent, (4) white specks, (5) 
streaked, (6) wavy, (7) mottled, (8) acid-cut, (9) 
high, (10) light, (11) uncolored. 

( 1 ) Perfect color in cheese is indicated by even- 
ness of color throughout the mass. A plug held 
between the eye and light should appear somewhat 
translucent. 

(2) Straight color Is an even, uniform color 
through the whole cheese. 

(3) Translucent applies to color in cheese which 
appears slightly translucent when the plug is held 
between the eye and the light. 

(4) White specks is a term that describes itself. 
Such specks in cheese are a defect. They may 



JUDGING COMMERCIAL QUALITIES 89 

appear in cheese cured at low temperature (p. 

332)' 

(5) Streaked color indicates that there are light- 
colored portions in the form of streaks. 

(6) Wavy color applies to lighter portions appear- 
ing in the form of waves. 

(7) Mottled color shows in cheese in lighter- 
colored spots of fairly large size, more or less 
irregular. 

(8) Seamy color applies to the appearance of a 
pale rim surrounding each piece of curd and showing 
the outline of the pieces as they were before being 
pressed (p. 131). 

(9) Acid-cut color is shown in cheese when con- 
siderable portions of the cheese have been made 
lighter in color by the presence of too much acid 
( whey). 

(10) High color is indicated by a reddish color, 
caused by using too much coloring-matter. How- 
ever, the question of color is a relative one, because 
the demand in different markets varies from uncolored 
to extremely high color. 

(11) Light color is the term usually used in de- 
scribing cheese that has been made uniformly dead 
white by the action of too much acid (whey). 

(12) Red spots are places, usually small in area, 
having somewhat the appearance of iron-rust (p. 

131). 

(13) Uncolored cheddar cheese Is not white, but of 
a light amber shade. 

Salt. — The amount of salt in cheese varies some- 
what with different markets. There is seldom 
experienced difficulty of uneven salting in cheese. 



90 SCIENCE AND PRACTICE OF CHEESE-MAKING 

because the salt slowly permeates the cheese in the 
ripening process. Little variations usually occur in 
different parts of the same cheese, but are so slig-ht 
as to be incapable of being noticed by ordinary 
methods of examination. 

Testing cheese for salt. — The quality of cheese 
as influenced by the salt is found simply by 
tasting. 

Terms used in describing salt. — In describing 

the relation of salt to cheese, the following terms 

are used: (i) Perfect, (2) too much, (3) too 
little. 

(i) Perfect applies to salt in cheese when just 
enough has been used to impart a sufficient taste 
of salt. 

(2) Too much salt is indicated by salty taste. Too 
much salt in cheese causes a dry, mealy, overfirm body 
and imperfect flavor. 

(3) Too little salt is shown by insipidity of taste. 
It is usually accompanied by bitter flavor and porous 
texture. 

Appearance. — This term refers to the general 
appearance of the cheese to the eye in respect to 
uniformity, neatness and cleanliness. It may also 
include the boxing. One system, as in the case of 
butter, describes under "finish" the appearance of the 
cheese, and under ''packages" the boxing; and we 
will follow this method here. 

Testing appearance. — When the cover of the box 
is removed for sampling, in the case of boxed 
cheese, the appearance of the cheese is noticed and 
the box itself is examined. Cleanliness and neat- 



JUDGING COMMERCIAL QUALITIES QI 

ness are the points to observe in judging appear- 
ance. 

Terms describing appearance. — The general terms 
used in describing appearance are (i) finish and (2) 
package. 

(i) Finish in appearance, in order to be perfect, 
must meet the following requirements : The rind 
must be smooth, even in color, free from cracks 
and fairly hard. The bandage must be without 
wrinkles and must be neatly rounded over the edges 
about an inch on each end of the cheese. The sides 
of the cheese should be straight and of uniform 
height all around. 

The faults of appearance in finish are as fol- 
lows, the terms being self-descriptive : ( i ) Cracks, 
(2) light spots, (3) roughness in rind, (4) uneven 
edges, (5) wrinkles in bandage, (6) lack of uni- 
formity in ends and in height, (7) bulging out at 
sides or ends. 

(2) Package. — The packages or boxes are re- 
garded as perfect when of good material, well made, 
strong, clean, close-fitting, uniform in size and in 
undamaged condition. 

JUDGING AND SCORING CHEESE 

The qualities described in the preceding pages 
are used for judging and fixing the commercial 
value of cheese. Judging cheese consists in making 
an examination of a cheese with reference to the 
various points of quality, which have been de- 
scribed in the foregoing pages, as a basis for scor- 
ing cheese, which consists in assigning to each 



92 SCIENCE AND PRACTICE OF CHEESE-MAKING 

quality a definite value, corresponding to its char- 
acter as found in the cheese examined. In judging 
cheese one must have in mind (i) the perfection 
of quality in each case as a basis for comparison, 
and (2) the proper perspective of the dififerent 
qualities in relation to each other. 

Scale of points. — To each quality is assigned a 
definite numerical value and these numbers are called 
a scale of points. The different values assigned to 
the various qualities indicate perfection in each 
case and the totals aggregate lOO. Slightly differ- 
ent values are assigned in different cheese markets 
and for cheese made by different variations in the 
process of manufacture. Below we present ex- 
amples of different types of scale of points: 





Export cheese 


Home-trade cheese 


English market 


Flavor 


45 
IS 
IS 
IS 
10 


50 
10 


35 


Texture 

Body 


IS 

25 (quality) 

15 

10 (make) 


Color 

Appearance 

(Finish) 



In the case of home-trade cheese, a larger num- 
ber of points is allowed for perfect flavor, because 
such cheese, on account of its high water-content, 
easily develops poor flavor and, consequently, 
flavor deserves more attention in judging and 
scoring than in case of export cheese, which, with 
smaller water-content, is more uniform in flavor. 
Then, again, in home-trade cheese, closeness of 
texture is not regarded as highly essential, the main 
emphasis being given to body. 



JUDGING COMMERCIAL QUALITIES 93 

In explanation of the English scale cf points, it 
may be stated that the majority of Englishmen pre- 
fer cheese of considerable age, properly ripened and 
rather sharp in taste, and it is this character which 
they express by the word "quality." 

Method of scoring. — In scoring a sample of 
cheese, an examination is made with reference to 
each of the qualities mentioned. In those qualities 
in which it is perfect, it is given the values or 
points assigned above. If the cheese is defective 
in any quality, that is, short of perfect, then a 
smaller value is given than the one indicated above 
in the scale of points ; the more defective the cheese 
is in any quality, the lower is the value or number 
of points given it. When all the qualities have been 
scored, the numbers of points assigned to them are 
added and the total is the score of the cheese under 
examination. 

It can readily be seen that judgment, trained by 
experience, is required to assign to each quality its 
proper number of points. The sense of smell and of 
taste must be highly developed by training in the field 
of experience. The eye and touch must also be 
trained by special experience in the actual work of 
sampling, studying and judging cheese. 

Score-cards. — For convenience, score-cards are 
used in keeping records of the results of scoring 
where many samples are examined. The following 
form (see next page) illustrates a commercial score- 
card. 

In commercial scoring, reasons for the number 
of points given are not stated ; but in dairy schools 
and competitive public exhibitions, where educa- 
tional purposes are in view, the reason for each 



94 SCIENCE AND PRACTICE OF CHEESE-MAKING 



Name or number identifying sample 

Class or kind of cheese 

Date Judge . 



QUALITY 


Score-points 


Sample 
1 


Sample 
2 


Sample 
3 


Sample 

4 


Flavor 


45 
IS 
15 
15 
10 


42 
14 
14 
15 
10 


40 
13 

15 

14 

8 


36 
12 
12 
13 
10 


35 


Texture 


10 


Body 


10 


Color 


12 


Appearance 


8 








95 


90 


83 


75 



score should be given. The educational feature 
should be made especially prominent at country 
and state agricultural fairs, at conventions of dairy- 
men's associations, etc. There is, and has been, 
altogether too little attention given to the educa- 
tional feature ; the main, and usually the sole, pur- 
pose has been to capture prizes. Such occasions 
can be made extremely valuable in an educational 
way by indicating in detail the defects and then 
indicating hov^ these may be overcome. The follow- 
ing form of score-card for such purposes is a sugges- 
tion, which may be modified to suit any special 
conditions : 

EDUCATIONAL CHEESE-SCORING CARD 



Date Judge . 

Class 

Name or number identifying cheese . . . . 



NUMERICAL SCORE 
Qualities: Flavor Texture Body Color Appearance 

Pei?ec\£i: ) « '= " >' '» 

Score given : 

Total score ; 



JUDGING COMMERCIAL QUALITIES 95 

DESCRIPTIVE SCORE (Check defects in list below) 



Flavor 


Texture 


Body 


Color 


Appearance 


Perfect 


Perfect 


Perfect 


Perfect 


Perfect 


Clean Quick 


Close 


Firm 


Straight 


Finish: 
Perfect 


Flat Strong 


Porous 


Smooth 


Translucent 


Cracks, 
Light spots 


Too much acid 


Mechanical-holes 


Silky 


Light 


Rough rind 


Too little acid 


Pin-holes 


Waxy 


High 


Une'n edges 


Sour Bitter 


Swiss-holes 


Pasty 


Mottled 


Uneven ends 


Cowy Stable 


Fish-eye-holes 


Weak-bodied 


Streaked 


Wrinkles 


Sweet or frtiity 




Stiff or corky 


Wavy 


Bulging 


Weedy Rancid 




Crumbly 


White specks 


Packages* 


Tallowy Fishy 




Gritty 


Creamy 


Perfect 


Tainted 




Watery 


Acid-cut 


Clean Dirty 


Hydrogen-sulphid 




Overdry 


Red spots 
Uncolored 


Neat Unif'm 
Loose Close 



Remarks 

Advice for overcoming defects . 



Methods of grading cheese. — The classification 
of cheese according to the residts of judging and 
scoring varies in different markets, the method in 
each case being arbitrary. For ilhistration, one 
classification is into (i) ''fancy," (2) "firsts" and (3) 
"seconds." In the Canadian market, there are first, 
second and third grades. 



CHEESE-MAKERS AND JUDGING CHEESE 

It is a matter of regret that cheese-makers do 
not have more extended practical experience in 
judging cheese. Every cheese-maker who desires 
to acquire greater efficiency in his work should 
own a good cheese-trier and use it as often as 
practicable. It is well before shipment to examine 
one cheese from each day's make and then study 



g6 SCIENCE AND PRACTICE OF CHEESE-MAKING 

the results in connection with the record of corre- 
sponding date, giving the details of the conditions 
of manufacture. This is frequently impracticable, 
because cheese is shipped before it can be properly 
judged. Then, again, cheese which appears well when 
shipped may develop imperfect qualities later; while 
some cheese, imperfect at the start, may improve later 
if kept under proper conditions. 



CHAPTER IX 

Cheese-Factory Construction 

A cheese-factory should be a model of cleanliness 
in every dairy community. At the present time the 
word cheese-factory does not stand for any such ideal 
condition. In the construction or remodeling of fac- 
tory buildings, attention should be given to the follow- 
ing points: (i) Location and site, (2) material to 
be used, (3) architecture, (4) water-supply, (5) 
drainage, and (6) curing-rooms. 

LOCATION AND SITE 

The selection of a suitable location and site is one 
of the most important factors in cheese-factory con- 
struction. The factory should be centrally located 
and, if possible, on a hillside where advantage may be 
taken of gravity and other natural conditions. 

Before we were familiar with the importance of 
sanitation, cheese-factories were invariably erected on 
low, wet ground where a water-supply could easily 
be obtained. No attention was paid to the means of 
disposing of the excess of whey and of sewage from 
the building. The result was that in a short time the 
soil surrounding the factory became saturated with 
decayed waste products ; the water-supply was made 
impure from the same source ; in hot weather, flies 
gathered in large numbers, carrying bacteria and dirt 

97 



98 SCIENCE AND PRACTICE OF CHEESE-MAKING 

from the stagnant surroundings into the vats con- 
taining milk and curd. As a result of these condi- 
tions, bad flavors appeared in the cheese, and cheese- 
makers experienced all sorts of difficulties in the 
factory operations. Most of these bad conditions 
have since been removed or remedied, but in many 
parts of the country they are still to be found. In 
Ontario, Canada, especially, great improvement has 
been made in the sanitation of cheese-factories since 
the passing of a special law and the appointing of 
special sanitary inspectors. Most factorymen now 
appreciate the value of cleanly conditions surrounding 
the entire manufacturing process, but many must be 
forced to put their buildings and equipment in proper 
condition. 

MATERIAL TO BE USED 

Appearance, cheapness, durability and efficiency 
should be kept in mind. Brick buildings are to be 
preferred, and, while their first cost is greater than 
wood, they are the most durable and cheapest in the 
end. Cement, when properly made and used, makes 
an efficient, fairly cheap and durable building. Stone 
and wood are commonly used. The relative economy 
with which the building material can be obtained will 
largely influence the character of buildings erected in 
diflferent localities. 

ARCHITECTURE 

Plans and blue-prints of modern cheese-factories 
are always available, free of charge, from the agricul- 
tural departments of the diflferent governments, so 



CHEESE-FACTORY CONSTRUCTION 99 

that it is unnecessary in this treatment of the subject 
to go into details. Suffice it to say that the architec- 
ture should be simple, attractive and convenient. The 
location and site will determine to a great extent the 
style of architecture. 

WATER-SUPPLY 

Nothing is of more importance in factory construc- 
tion than the water-supply. The quality should be 
pure and an abundance of it should be assured. The 
purity of springs, deep wells, rivers, and lakes with 
a large outlet can usually be depended upon, but the 
character of the surrounding area drained must be 
considered. Surface water, by all means, should 
be kept out of the wells. If milk or whey enters a 
well accidentally or otherwise, the water soon becomes 
contaminated and unfit for use. When this occurs, 
the water should be pumped out and the well thor- 
oughly cleaned. 

DRAINAGE 

Drainage is so closely related to the water-supply 
that they are naturally considered together. If pos- 
sible in any way, natural drainage should be secured. 
In cheese-factory work there is usually a considerable 
volume of sewage, consisting of wash water and 
excess of whey. The best method for its disposal 
is now attracting the attention of factorymen and 
of those who enforce the laws of health and sanita- 
tion. The character of sewage at all cheese-factories 
is practically the same. The method of its disposal 



lOO SCIENCE AND PRACTICE OF CHEESE-MAKING 

will depend on the water content, the character of the 
constituents, and slope of the surrounding soil. The 
waste or superfluous whey is the main cause for need 
of improved sanitation at cheese-factories. If it 
were not for this, the wash water could be more 
easily disposed of. However, the following- methods 
have given excellent satisfaction when properly in- 
stalled under suitable conditions. 

Removal by cartage. — This system requires a 
storage-tank for wash water as well as for whey, 
although many factorymen allow the wash water to 
run into the whey-tank. Arrangements are made by 
which some person agrees to remove all sewage from 
the factory to some river, lake or satisfactory place 
of disposal and to clean the whey-vats at stated times 
in return for the superfluous whey he may receive 
to use for feeding purposes. As a rule, this method 
is satisfactory, and its use is advised when the others 
are not more practicable. 

Direct disposal into large lakes and running 
streams of water. — Many factories are located on 
the banks of lakes and rivers, into which it is usually 
an easy matter to conduct the sewage by means of 
piping or tile. This makes an ideal method, if the 
body of water is large or has sufficient current to 
carry it to a suitable outlet. 

Septic-tank system. — This consists of a series of 
tanks, in which the sewage is treated before being 
allowed to flow out into or on top of the surrounding 
ground. The number and size of tanks will depend 
on the size of the factory and the character of soil 
into which the treated sewage must pass. Fig. 20 
illustrates a plan for a factory with a daily capacity 



CHEESE-FACTORY CONSTRUCTION 



101 



for 10,000 pounds of milk, whose treated sewage 
passes out into heavy soil with little natural drainage. 
The material used in tank construction can be iron, 
cement or wood. Each part should be large enough 
to hold the sewage of 24 hours. By this arrangement 
the sewage is in the tank for three days. At the 
end of this period it may be carried by piping or tile 
to its final place of deposit. The overflow-pipes 
should be ventilated to prevent siphoning of the con- 
tents after it starts to overflow. The tanks are 



7^ 



SEWAGE 

SECOND 

OAV 



,4' SOIL TILE 



SEWAGE 
THIRD 

OAV 




DISPOSA 

FIG. 20 — SERIES OF SCEPTIC TANKS CAPABLE OF HOLDING 
THREE days" SEWAGE FROM A CHEESE-FACTORY HAN- 
DLING 10,000 POUNDS OF MILK A DAY 



better placed under ground so that the top just 
reaches the surface. It should have a good top and 
may then be covered with earth. It is advisable to 
have a water-trap in the pipe delivering the sewage 
from the factory to the septic tank in order to pre- 
vent odors returning. This system is very efficient 
and may be used in almost any locality. In some 
places it is advisable to deposit the treated sewage 
on a prepared, gravel filter-bed. 



102 SCIENCE AND PRACTICE OF CHEESE-MAKING 



Cesspools. — When the surrounding soil is of sand 
or gravel, the cesspool makes an efficient and cheap 
method for sewage disposal. For a factory with a 
daily capacity of 10,000 pounds of milk, a cesspool of 
the following dimensions and construction is ad- 
vised: A hole 12 feet in diameter and 6 feet deep 
is excavated. This should be lined with loose stones 
up to within one foot of the ground surface. Over 
this, cedar logs, with good supports, are placed at 
intervals of 24 inches. A plank covering goes over the 
logs, and this again is covered with earth, making the 



^QR 
nLLiN6 



TT 



SLIDE TRAP DOOR 



SOLID ICE 



SLIDE. TRAP DOOR -L 
ORAIN 



^ 



CURINB ROOM 



J 



S- SHAPED T'PIPE FROM 
DRA)N IN ICE-HOUSE 

FIG. 21 — PLAN SHOWING SATISFACTORY METHOD FOR 
ING CIRCULATION OF COLD AIR IN CHEESE-CURING 



SECUR- 
ROOMS 



Spot unnoticeable. A cesspool should be located at 
least 20 feet away from the buildings, and on the lower 
side of the source of water-supply. The pipe lead- 
ing from the factory floor to cesspool should have 
a water-trap to prevent returning odors. It is advis- 
able to place on all whey-tanks an overflow pipe con- 
nected with the drainage deposit. 



CURING-ROOMS 

A curing-room should be so constructed that the 
temperature and humidity can be controlled. It should 



CHEESE-FACTORY CONSTRUCTION 



103 



have good ventilation, insulation and circulation of 
pure air. Under ordinary conditions, ice provides 
the cheapest and most efficient method of maintaining 
a uniformly cool temperature in curing-rooms. In 
large cheese-making centers, artificial refrigerating 
machines are used, but they are too costly for ordinary 
cheese-factories. Sub-earth ducts have proved unsatis- 
factory, since they are too often least efficient when 
most needed. 



DRAINAGE DISPOSAL^ pEPTIC tanks OR CESS-POOL 



WHEY TANKS 



o 



iCf HOUSE 



STORE - 
ROOM 



COAL A. 
WOOD 



BOILER ROOM 



PRESS I 



STARTER 
I ROOM 

ISINK A 

WASH 

[ROOM 

WEIGH 

o 



FIG. 22 MODERN PLAN SHOWING IDEAL ARRANGEMENT 

CHEESE-FACTORY ROOMS AND EQUIPMENT 



OF 



The drawing on page 102 (Fig. 21) provides a 
scheme by which the air in the curing-room has a 
continuous circulation over a bed of solid ice 

The curing-room and ice-house should have good 
insulation secured by the use of lumber, building- 
paper, air-spaces, shavings and cement floors. The 
ice-house should be one-third the size of the curing- 
room. Three thicknesses of lumber, one of damp- 
proof paper, and 6 inches of shavings provide 



104 SCIENCE AND PRACTICE OF CHEESE-MAKING 

sufficient insulation for the curing-room. For the ice- 
house an extra thickness of kunber and damp-proof 
paper is advised in both ceihng and wall construction. 
The ice-house floor and walls halfway up are lined 
with galvanized iron. 

The construction of the floor in the ice-house is 
important, as provision must be made for protecting 
the ice from the warm temperatures of the soil under- 
neath. A cement floor with gravel and stone support 
is first constructed. Over this, 2-inch by 4-inch sup- 
ports are placed on edge at intervals of 18 inches. 
Between these the space is filled with coal cinders 
or shavings. Over this a 2-inch plank floor is laid, 
and this covered with galvanized iron. A drain 2 
inches by 2 inches should .be made in the ice-house 
floor close to the curing-room wall, toward which 
the ice-house floor should incline. The drain is neces- 
sary to carry off the water from the melting ice. A 
close-fitting S-shaped pipe with water-trap should 
connect the drain with outside disposal. Over the 
galvanized floor is placed a rack made of 2-inch by 
4-inch supports on edge. This prevents the ice from 
lying in water when it starts to melt. During the 
winter months, the ice-house is packed full of ice. 
No sawdust is used, the insulation being sufficient to 
protect it 

As Figure 21 shows, small trap-slides are placed 
near the ceiling and floor between ice-house and cur- 
ing-room. As soon as these are opened, the warm air 
in the curing-room enters the openings at the top, 
passes over the ice and out through the lower openings, 
thus creating a circulation of cold air through the 
curing-room. A uniform temperature of from 52° 



CHEESE-FACTORY CONSTRUCTION 



105 



to 56° F. can be secured throughout the entire sum- 
mer season in this way, and a uniform percentage of 
moisture is also assured 

When this system is not used, the curing-room air 
may be cooled by hanging up large pans filled with 
ice, but the moisture from them generally stimulates 
mold formation. Where cold running water is avail- 
able, it can be conducted through a system of coil- 
pipes around the walls of the curing-room and the 
temperature considerably lowered. 




FIG. 23 — PLAN FOR CHEESE-FACTORY HANDLING 12,000 TO 

20,000 POUNDS OF MILK A DAY. (Bacr) 



shelves. 



CHEESE-FACTORY PLANS 



As a suggestion, we give the outline of a plan for 
cheese-factory construction with special reference to 
convenience of arrangement for equipment. (Fig. 
22.) 

We give also an outline plan published by Ij. S. 
Baer, of Wisconsin. (Fig. 23.) 



CHAPTER X 

Cheese-Factory Equipment 

A cheese-factory should be equipped that every- 
thing may be easily kept clean. The vats, presses, 
sinks and all utensils should be placed in positions 
that will insure convenience and a minimum amount 
of labor. Too many factories at the present time 
are not large enough for the equipment they contain, 
and they consequently appear untidy and dirty to 
visitors or to persons inspecting the conditions sur- 
rounding the manufacturing process. Very often^ too, 
the utensils are not clean, for the reason that the 
cheese-maker, being short of help, neglects part of 
the work. Utensils and equipment, properly ar- 
ranged, will save a great many steps to the cheese- 
maker in a day. (Figs. 22 and 23.) 

Advice, which is the result of varied experience and 
which is often of considerable help to persons in need 
of such assistance, can always be secured from ex- 
perts employed by the different departments of agri- 
culture. 

The following apparatus is sufficient for a factory 
handling 10,000 pounds of milk daily. 

(i) One i2-horse-power, return-flue, horizontal 
boiler with fixtures. 

(2) Two steam-heating cheese-vats, with a capac- 
ity of 7,000 pounds each. In recent years, wood suit- 
able for making cheese-vats has become expensive and 
hard to secure. Many manufacturers are using wood 

106 



CHEESE-FACTORY EQUIPMENT 



107 



of a poorer quality, and the vats are not durable. 
Steel vats have been placed on the market and are 
giving general satisfaction. They are preferable to 
the average wooden vat now manufactured. (Fig. 
24.) 

(3) Whey-tank, capacity of 12,000 pounds. If the 
factory is so located that its elevation permits the load- 
ing of whey without pumping, then one large tank can 
be used. However, two smaller tanks connected by 
an overflow-pipe are* preferable, because, when one is 
empty, it can be cleaned while the other contains whey. 
Steel tanks are preferable to wooden or cement ones. 
They neither leak nor absorb, are easily cleaned, and 
are more durable. Cement tanks are not durable, 




FIG. 24 — ONE TYPE OF STEEL CHEESE-VAT 

because the acid and salt in the whey destroy the 
cement. 

(4) One 600-pound, double-beam scale. Scales 
are in daily use at cheese-factories and it is advisable 
to purchase only those that are reliable and guaran- 
teed, such as the "Fairbanks" and "Howe." 

(5) One 70-gallon weighing-can with a 3-inch 
gate. 

(6) One milk-conductor and head. 

(7) Apparatus and alkali for testing acidity. 



lo8 SCIENCE AND PRACTICE OF CHEESE-MAKING 



(8) One Marschall or Monrad rennet-test. 

(9) One 3-8-inch, horizontal, steel curd-knife. 

(10) One 5-16-inch perpendicular, wire curd- 
knife. 

(11) Two small solid-handle dippers. 




FIG. 25 — Barnard's curd-cutter 

(12) One strainer-dipper. 

(13) Two curd-agitators of McPherson type. 

(14) Two curd-rakes. 

(15) Two thermometers, strictly correct and reli- 
able. 

(16) One outfit for making commercial starters. 




FIG. 26 — GOSSELIN CURD-MILL 



(17) Two whey-strainers for each vat. 

(18) One large knife for cutting curd. 

(19) One curd-mill. A curd-mill should be so 
constructed that its knives will go against the curd 



CHEESE-FACTORY EQUIPMENT 



109 



in cutting. The curd should not be pushed against 
the knives. Such mills as the Barnard (Fig. 25), 
Beech and Gosselin (Fig. 26) are recommended. 
They can be had in hand or steam-power. 

(20) Two curd-stirring forks of wood or steel, 
with points turned over so as not to puncture the tin 
vats during stirring. 

(21) One curd-scoop. 

{22) One flat-sided curd-pail. 

(2^) Two steel-frame, automatic, continuous-pres- 
sure gang-presses with hoops, followers, etc., com- 




FIG. 27 — CONTINUOUS-PRESSURE GANG PRESS 

plete. (Figs. 2y and 28.) Galvanized-steel followers 
are preferable to wooden ones, as they are more sani- 
tary, are not absorbent, do not expand or contract in 
hot water, and are more durable. Galvanized rings 
are preferable to the fiber or rubber ones for the same 
reasons. 

(24) One 240-poun(l cheese-scale. 

(25) One 24-bottle Babcock milk-tester. 

(26) Two composite-sample bottles for each 
patron. 



no SCIENCE AND PRACTICE OF CHEESE-MAKING 



{^2y) If the whey is to be separated and whey- 
butter made from the fat, a separator and machinery 
for butter-making will be necessary. 

(28) An instrument for determining the amount 
of moisture in the air of the curing-room. (Fig. 

29-) 

(29) A sterilizing-oven for sterilizing milk to be 
used in the preparation of starters and also for the 
sterilization of the smaller utensils employed in the 
cheese-factory will be found convenient and highly 
useful. Home-made sterilizers can be used with good 




FIG. 28 



FRASER HOOP 



WILSON HOOP 



A— Complete hoop; B— Bandages; 
C— Follower; D— Fibrous press-ring. 



A— Complete hoop ; B— Bottom cov- 
er with wide flange ; C— Top cover with 
narrow flange ; D — Closed or tight hoop 
or body; E— Open hoop or bandages. 



results. A galvanized-iron box, double- jacketed, is 
arranged to admit steam between the walls. An open- 
ing in the top of the outside wall is arranged to regu- 
late steam pressure and another at the bottom to carry 
off condensed water. The outside may be protecte*d 
by a covering of asbestos or other boards. 
(30) One Quevenne lactometer. 



FACTORY FURNISHINGS 

Fuel, coal or wood. 

Rennet-extract (Hansen's is recommended). 



CHEESE-FACTORY EQUIPMENT 

Cheese color (Hansen's is recommended). 

Commercial starter. 

Vat-brooms. 

Floor-brush. 

Washing-powder. 

Cotton for press-cloths. 



Ill 




HYGRO-AUTOMETER 



FIG. 29 — APPARATUS FOR INDICATING 

PERCENTAGE OF MOISTURE IN AIR 

OF CURING-ROOM 



Cheese-bandage. This should be seamless and the 
size yi inch smaller than the diameter of hoops; a 
cheese retains its shape better with such bandage. 

Cheese circles. 

Cheese salt. Paper-lined barrels are preferable. 
The salt should be regular cheese-salt. Fine butter- 
salt dissolves too rapidly and does not penetrate the 



112 SCIENCE AND PRACTICE OF CHEESE-MAKING 

curd so well. Such brands as Windsor, Diamond, 
Crystal, Genesee, LeRoy, Warsaw and Worcester are 
generally reliable. 

Cheese-boxes. These are made of both wood and 
paper. If properly made, either material is satisfac- 
tory. The boxes should be strong enough to stand 
handling in shipping, and they should fit the cheese. 
One-quarter inch between the cheese and box is suf- 
ficient. 

Scale-boards. 

Milk-sheets. 

Blanks for records of conditions of cheese-making 
(p. i6). 

Blanks for reports to patrons. 

Milk-record books. 

Cheese-shipping books. 

Materials and stencils for branding boxes. 

It is a great mistake for factorymen to purchase 
cheap furnishings just because they are cheap. Cheese 
of the best quality is the most profitable to make, and 
no cheese-maker can afford to use poor furnishings if 
he expects to have his cheese of finest quality and 
appearance. 



Part II 

Defects of American Cheddar 
Cheese in Flavor, Body, Tex- 
ture, Color and Finish: 



Causes 

Remedies 

Means of Prevention 



CHAPTER XI 

Defects in Flavor 

In this and several chapters following, an effort 
is made for the first time to present in systematic 
form a discussion of the imperfections that are most 
commonly found in our American cheddar cheese. 
The need of this requires no explanation, and the 
importance of the subject is only too obvious. The 
extent of defects in our cheese is well known and 
also their demoralizing effect upon the industry. In 
reality, the whole aim of the cheese-maker is, of 
course, to produce cheese free from imperfections. 
In discussing the subject, it is necessary to know (i) 
what the defects are, and (2) to what causes they 
are due. We are then in position to consider remedies 
and means of prevention. The subject will be pre- 
sented under the following divisions : 

Defects in 

( 1 ) Flavor. 

(2) Body. 

(3) Texture 

(4) Color. 

(5) Finish. 

In each division, the presentation will give (l) 
description of defect, (2) causes, (3) methods of pre- 
vention and (4) remedies. It is important to know 
how to prevent the recurrence of conditions that are 
responsible for cheese-making troubles, and also how 



Il6 SCIENCE AND PRACTICE OF CHEESE-MAKING 

to handle the details of the cheese-making- process 
when the presence of the trouble is recognized. The 
facts will be presented more or less in outline form, 
in order to make reference to them more convenient. 

ACID FLAVORS 

These are indicated by a sour smell and taste. 
Cause : 

(1) Over-development of acidity during the process of 

cheese-making, which is commonly due to — 

(a) Ripening the milk too much before adding 
the rennet. 

(b) The use of too much starter. 

(c) Failure to firm the curd sufficiently before re- 
moving the whey. 

(2) Any condition that retains in the curd and cheese an 
excessive amount of whey (p. 46). 

Prevention : 

(1) Have less acidity in the milk before adding rennet- 

extract. Sour milk, or milk over 0.26 per cent in 
acidity, should not be accepted from any patron. 
High acidity can be overcome by patron, if he will 
cool milk to 60° F., or better 50° F., at once after 
milking. 

(2) Use less starter. Generally ^ to 2 per cent is suiftcient. 

(3) Add the rennet when such a degree of acidity is 

present that the curd will become firm in the whey 
before developing the desired amount of acid. 

Remedy : 

(See the treatment given under remedy for acid body (p. 122). 

OFF FLAVORS 

These are flavors that are not clean, such as rancid 
or butyric acid flavor, stable or cow-manure flavor, 
fishy flavor and hydrogen sulphid or sulphur-spring 
flavor. When these develop so as to become very 
strong, they are called "stinkers." 



DEFECTS IN FLAVOR II7 

Cause : 

Undesirable bacteria, which gain entrance to the milk or 
to the curd some time during the manufacturing process, 
commonly due to — 

(1) Failure of patrons thoroughly to wash and scald all 

cans and utensils coming in contact with the milk. 
This is particularly true of cans in which whey is 
carried from the factory, 

(2) Careless milking in unclean places. 

(3) Allowing the milk to become exposed, after milking, 

in places where the air is impure. 

(4) Keeping the milk at too high temperature. 

(5) Using an unclean strainer at either the farm or cheese- 

factory. 

(6) Using utensils in the factory that have not been 

thoroughly cleaned and scalded. 

(7) Using badly-fiavored starters. 

(8) Using impure water for diluting rennet. 

(9) Soaking curd in impure water after milling. 

(10) Using tainted rennet or salt. 

(11) Ripening cheese at temperatures above 65° F. 
Prevention : 

Strict cleanliness in the production and handling of 
milk and throughout the whole cheese-making process 
(pp. 8, 17). 

(1) All utensils, especially the milk-strainer, should be 

thoroughly washed with warm water, using washing- 
powder, and then scalded with live steam. 

(2) Milking should be done in clean places, where dust, 

cobwebs and flies are not present. 

(3) Milk should be oooled to at least 60°, and better 50° 

F., immediately after being drawn from the cow. 

(4) Tainted milk should not be received at the factory 

from any patron. If uncertain of the source of 
tainted milk or curd, use the fermentation test on 
each patron's milk (p. 434). 

(5) A small amount of clean-flavored starter should be 

used. 

(6) Impure or bad-smelling water should not. be used. 

(7) There should be screens on the doors and windows to 

prevent the entrance of flies. 

(8) When curd is washed, only pure water should be 

used. 
Remedy : 

(1) Firm the curd a little more than usual in the whey by 
raising the temperature. 



Il8 SCIENCE AND PRACTICE OF CHEESE-MAKING 

(2) Develop a little more acidity before removing all the 

whey. 

(3) Mill the curd early and expose well to fresh air by 

stirring for some time immediately after. Excellent 
results can be secured at this time because each 
small piece of curd has six freshly cut surfaces which 
permit the gases and odors to escape. 

(4) Increase the amount of salt in curd in extremely bad 

cases. 

(5) Ripen the cheese at low temperature. 

FRUITY FLAVORS 

These are sweet flavors, having an odor like that of 
certain ripe fruits, such as pineapple, raspberry and 
strawberry. Such flavors are not pleasant to the taste 
and are rather sickish. 
Cause : 

(1) Bacteria or yeasts carried into the milk by dirt. 

(2) Transporting both milk and whey in the same cans 

when not properly cleansed. 

(3) Exposing milk near hog-pens where whey is fed. 
Prevention : 

(1) Cans used for delivering milk should not carry whey, 

unless they are emptied and thoroughly cleansed 
immediately after being brought from the factory. 

(2) All whey should be pasteurized at the factories. This 

would not only reduce greatly the source of badly 
flavored milk, but it would eliminate the danger of 
transmission of tuberculosis through the whey. 

(3) The whey-tanks should be cleaned and scalded at 

least twice a week. A steel tank has the following 
advantages: It is more durable than wood or ce- 
ment, does not leak, does not absorb whey, is easily 
cleaned, and is cheaper in the end. 

(4) Use a clean-flavored commercial starter. 
Remedy : 

(1) Firm the curd a little more in the whey by raising the 

temperature. 

(2) Develop a little more acidity before removing whey, 

(3) Air the curd well after milling. 

(4) In extreme cases use more salt in the curd. 



DEFECTS IN FLAVOR llQ 

BITTER FLAVORS 

Indicated by a bitter taste and a weedy odor. 
Cause : 

(1) Bacteria and yeasts. 

(2) Allowing cows to wade in and drink from stagnant 

pools. 

(3) Using rusted milk-cans or other utensils. 

(4) Using old starters that have developed toe much acid. 

(5) Using milk delivered in cans in which sour whey irom 

dirty tanks is carried. 

(6) Too little salt in curd. 
Prevention : 

(1) Milk should be cooled to at least 60° F., and better to 

50° F., immediately after milking. 

(2) Rusted cans or utensils of any kind should not carry- 

milk. 

(3) Cows should have only good water. 

(4) Clean-flavored starters only should be used. 

(5) Avoid the use of too little salt in the curd. 
Remedy : 

(1) Very little acidity should be developed before remov- 

ing the whey. 

(2) Firm the curd more than usual. Heat it higher in the 

whey and stir it drier when removing the whey. 

(3) Mill early and expose well to fresh air by stirring. 

(4) In extreme cases use more salt in the curd. 

FOOD FLAVORS 

These include flavors characteristic of the foods 
eaten by cows. A food flavor can be distinguished 
from one produced by bacteria in that a bacterial 
flavor usually gets worse as the cheese ages, while a 
food flavor generally passes off to some extent (p. 8). 
Cause : 

(1) Such foods as turnips, onions, leeks, weeds, garlic, 
rape, decayed ensilage and certain green fodders 
(p. 7). 



I20 SCIENCE AND PRACTICE OF CHEESE-MAKING 

(2) Exposing milk in an atmosphere where any of these 

are exposed. 

(3) Storing milk in cellars where decayed vegetables are 

present. 

Prevention : 

(1) Foods that impart any objectionable flavor to milk 

should not be fed or made accessible to the cow. 

(2) Use a good commercial starter. 

(3) Careful and thorough aeration (p. 12) of milk is often 

helpful in removing odors derived from foods 

Remedy : 

(1) Heat the curd several degrees higher in the whey. 

The high temperature helps to drive off the volatile 
flavors. 

(2) Air the curd well, especially after milling. 

(3) Ripen the cheese at a low temperature. 



CHAPTER XII 

Defects in Body and in Texture 

Dry Body 

Shown in cheese that is too firm, mealy, rubbery 
or corky. 
Cause : 

Lack of moisture or milk-fat or both, produced by — 

(1) Removing part of the fat from milk. 

(2) Too high heating in the whey. 

(3) Heating too long. 

(4) Too much stirring at the time of removing the whey. 

(5) Using too much salt. 

(6) Curing cheese in an atmosphere that is too dry or too 

hot. 

(7) A "high-cooked" cheese is rubbery or corky; one that 

has been stirred too dry is mealy or sandy; and one 
that is dry from excess of salt tastes salty. This is 
a convenient way of determining the cause of such 
defects. 

Prevention : 

(1) All the milk-fat should be retained in the cheese as 

far as possible. 

(2) The lower the temperature used in properly firming 

the curd, the better will be the texture of the cheese. 

(3) Be absolutely sure of the correctness of the thermome- 

ters used. 

(4) Give attention to the moisture content of the curd; 

stir the curd as conditions require; and use the 
proper amount of salt. 

Remedy : 

(1) Pile dry curd higher. 

(2) Keep the air moist by placing hot water in the vat. 

(3) Do not mill the dry curd early. 

(4) A dry curd can be made mellow by soaking in cold 

water after milling, but the cheese will not have 
good-keeping quality. 

(5) Use less than the usual amount of salt. 

121 



122 SCIENCE AND PRACTICE OF CHEESE-MAKING 

(6) Paraffin the cheese as soon as possible. 

(7) Ripen the cheese in a cool room where the humidity 

of the atmosphere is at least 80 per cent. 

ACID BODY 

Cheese under this head may be either dry or moist, 
but in either case is of a mealy or sandy character. 
It has a sour taste. 
Cause : 

(1) Overripe milk. 

(2) Ripening the milk too much before adding the rennet. 

(3) The development of too much acidity during the 

cheese-making process, especially before the whey 
is removed. 

(4) Acid or sour cheese is most frequently caused not hy 

developing too much acidity, but by having the 
curd insufficiently firm in the whey when the acidity 
has developed. 

(5) Using large amounts of starter. 

Prevention : 

(1) No sour milk, or milk containing more than 0.26 per 

cent of acidity, should be received from any patron. 

(2) The rennet should be added when the milk is at such 

a stage of ripeness that there will be time to firm 
the curd in the whey before too much acidi':y has 
developed. 

(3) Do not use too much starter. 

(4) Keep the development of acidity under control by 

controlling the amount of whey in the curd. 

Remedy : 

The method of handling overripe or sour milk, when it is 
absolutely necessary to make such milk into cheese, is as fol- 
lows: 

(1) Heat the milk not above 84° F. 

(2) Use an extra amount of rennet. 

(3) Cut the curd into smaller pieces. 

(4) Heat higher. The degree of heat will depend on the 

rapidity with which the acidity is developing. 
Most fast -working curd contracts rapidly and there- 
fore the raising of the temperature can be hurried. 



DEFECTS IN BODY AND TEXTURE 1 23 

(5) As soon as possible after heating, the whey should be 

run down to the level of the curd. This greatly 
facilitates stirring and firming the curd, and, if more 
than one vat is being used, time is saved when the 
remainder of the whey is to be removed. If by this 
time the curd is not firm and shows too much acidity, 
a sour cheese can be prevented by, 

(6) Removing the whey and putting on water at a temper- 

ature of 102° F. The amount of water used and the 
time it is left on will depend on the amount of 
acidity in the curd. In extreme cases, it may be 
necessary to give a second treatment with water. 
As soon as the curd becomes firmed in the water 
and the acidity is reduced to a normal amount, the 
water should be removed. The curd should then 
be treated like a normal curd. This method is not to 
be confounded with the "soaked-curd" process, 
which is entirely different . 

(7) If, after milling, the curd is sour, it can be improved 

by washing in pure water at 80° F. This resembles 
the "soaked-curd" process, and, as a rule, such 
cheese does not keep well. However, it is much 
better to do this than to allow the cheese to sour, 
and the process should be used in extreme cases. 

(8) Use an extra amount of salt after washing. 

LOOSE OR OPEN TEXTURE 

Cheese with this texture is full of holes. Such 
cheese is generally soft in body. Such defects are 
more serious when found in export cheese, since a 
*'close-boring" cheese is demanded for this trade. 
Cause : 

(1) Developing too little acid and retaining too much 

whey. 

(2) Putting curd to press at too high a temperature 

(3) Lack of pressing. 

(4) Soaking curd in water after milling. 

Prevention : 

(1) Have at least 0.24 per cent of acidity m whey run- 

ning from curd after it is piled for cheddaring. 

(2) The curd should be cooled to 80° F.,at least, before 

pressing. This can be hastened by running cold 
water around the outside of the vat lining. 



124 SCIENCE AND PRACTICE OF CHEESE-MAKING 

(3) Pressing for 48 hours is much better than for 24. 

A continuous pressure is of more value than a heavy 
pressure for a short time. 

(4) Curd should not be soaked in water. 

Remedy ; 

(1) Open-textured cheese can be closed up to some extent 

by pressing again. 

(2) Ripen at lower temperatures. 

GASSY CHEESE TEXTURE 

Indicated by the presence of pin-holes. Such 
cheese usually has a bad flavor, is spongy, and the curd 
may float on the whey in the early stage of cheese- 
making. 
Cause : 

(1) Milk infected by gas-producing bacteria, which are 

carried in by dirt. 

(2) Starters infected by gas-producing bacteria. 

Prevention : 

(1) Gassy milk should be not accepted from any patron. 

(2) Gassy starters should not be used. 

Remedy : 

The method of handling gassy milk or curd is as follows : 

(1) If it is known that the milk is gassy, use a safe 

amount of clean commercial starter. 

(2) Ripen the milk a trifle more before adding the rennet. 

(3) After cutting, stir the curd till the whey around it 

shows at least 0.1 5 per cent of acidity before heating. 

(4) Heat slowly. Take 30 to 60 minutes. 

(5) Care should be taken to have the curd not too firm 

in the whey before the acid begins to form. The 
acidity is a valuable guide at this time. 

(6) A little more acidity should be allowed to develop 

before removing the whey. About 0.32 per cent 
after all the whey is off is sufficient. 

(7) Should the curd float, remove the whey to such an 

extent that it can not float. 

(8) Pile gassy curd before and after milling. 

(9) After milling, the curd should be thoroughly stirred 

and aired before piling. The pressure causes the 
small pieces to become very thm. After the piling 



DEFECTS IN BODY AND TEXTURE I25 

and airing have been repeated a few times at inter 
vals of 15 to 20 minutes, most of the gases should 
have escaped. The pin-holes will then have be- 
come flattened and present a "dead" appearance. 

(10) The whey running from the curd at this time should 

show 1.2 per cent of acidity. 

(11) Cool the curd well before putting in press. 

(12) Press for 48 hours if possible 

(13) Ripen in a cool place 

GREASY TEXTURE 

This is indicated by the presence of free fat in the 
mechanical holes in the cheese. The surface of the 
cheese is usually greasy. This condition is most 
common in spring and in times of drouth. 

Cause : 

''1) Allowing separation and hardening or drying of cream 
on milk before manufacturing. In factories that 
do not take milk on Sunday, the trouble is always 
greatest on Monday. 

(2) Abnormal proportion of fat to casein in milk in times 

of drouth (p. 164). 

(3) Heating milk too high or too long before adding 

rennet . 

(4) Handling curd too roughly. 

(5) Piling curd too much. 

(6) Maturing curd at high temperature. 

(7) Using a mill that bruises the curd. 

(8) Ripening cheese at high temperatures. 
Prevention : 

(1) Make up the milk daily, or take pains to keep the 

cream stirred in, to prevent formation of dry lumps 
that cannot be worked back perfectly into the milk. 

(2) Cut and stir the curd very carefully while soft. 

(3) Do not pile the curd more than two la5^ers deep. 

(4) Do not heat the milk or curd too high. Be sure of the 

accuracy of the thermometer used. 

(5) Use a mill that cuts the curd without squeezing the 

fat from it. The knives should go against the curd 
and not the curd against the knives. 

(6) Apply the salt soon after milling and mature the curd 

after salting. 

(7) Ripen the cheese in a cool room. 



120 SCIENCE AND PRACTICE OF CHEESE-MAKING 

Remedy : 

(1) Rinse the curd with water at 90° F. before salting. 

Then use a trifle more salt. 

(2) Cool the curd before putting in press. 

(3) Use large, clean press-cloths to insure the formation 

of a good rind. 

(4) Use sufficient hot water at the time of dressing the 

cheese 

FISH-EYE TEXTURE OR YEASTY CHEESE 

This is indicated by holes or slits resembling the eye 
of a fish. (Fig. 30.) This is usually accompanied 
by a bitter flavor. The first indication of this tex- 
ture is the formation in the cheese of a number of 
small pin-holes surrounded by white rings. These 
gradually enlarge until the characteristic slit-like 




FIG. 30 — TYPICAL ILLUSTRATION OF THE SLIT-LIKE HOLES 
FORMED IN A "YEASTY"' CHEESE 

openings are formed. Usually they are most notice- 
able near the rind, but in advanced stages extend 
throughout the whole cheese. If present in colored 
cheese, the color may become badly mottled as the 
cheese ages. When the cause of this trouble is 
present in milk, there is a bitter taste, which be- 
comes more pronounced as the acidity of the milk 
increases. 



DEFECTS IN BODY AND TEXTURE 12/ 

Acidity usually appears in the milk quite slowly, even 
after the curd has been first cut. When the formation 
of acid once starts, It increases very rapidly. This is 
usually during the interval when the whey is removed. 
The acid increases rapidly and the curd tends to 
become soft or mushy. In the cheddaring process the 
curd may become more or less filled with large, shining 
openings, resembling gas-holes. After milling, the 
curd is usually very slow to contract and, in severe 
cases, may soften and lose its body. Frequently yeasts 
are accompanied by gas-producing bacteria and, when 
this combination is encountered in cheese-making, it 
is very difficult to make cheese of passable quality. 
Whey from such cheese, when whey tanks are not 
frequently cleaned, may appear to boil, as though over 
a fire. 

Cause : 

Yeasts which gain entrance to milk. They have been found 
on hay-dust, leaves of trees, in unclean cellars, and in whey- 
tanks. 

(1) In cheese -factory work, the whey tank is the great 

source of germ contamination. 

(2) Allowing milk to be exposed to the dust of stables 

after milking (p. 6). 

(3) Keeping milk too warm after placing it in the cans. 

Prevention : 

(1) After milk is drawn, it should immediately be taken 

into a clean atmosphere and cooled to 60° F., and 
better to 50° F. 

(2) Whey-tanks should be cleaned and scalded twice 

a week, at least, and, better still, every day. 

(3) All the whey should be pasteurized. 

(4) All cans and utensils used in carrying milk should be 

thoroughly cleaned and scalded. 

Remedy : 

When it is known that yeast -infected milk has been re- 
ceived, it should be treated in the following way: 



[28 SCIENCE AND PRACTICE OF CHEESE-MAKING 

(1) A good commercial starter should be used. 

(2) The rennet should be added when the milk is at such 

a stage of ripeness that there will be time to firm 
the curd m the whey before too much acidity has 
developed. 

(3) Use a higher temperature for heating. Generally 

about 2° F. higher is sufficient. 

(4) Remove the whey with as little acidity as is necessary 

to mature the curd properly in cheddaring. If a 
good starter has been used, an acidity of 0.24 per 
cent, after the whey is all removed and the curd 
packed, should be sufficient. 

(5) Stir the curd well at the time of removing the whey. 

(6) Do not pile the curd high in cheddaring unless gas is 

present. 

(7) Mill the curd early and air well immediately after. 

(8) Should the curd become mushy after milling, apply 

one-half the amount of salt to be used. Then in 
about an hour, or as soon as the curd has shrunken 
and the holes have closed, apply the balance of the 
salt. 

(9) Curing at low temperature helps to check the slit 

formation and the bitter flavor. 



CHAPTER XIII 

Defects in Color and in Finish 

PALE OR ACID-CUT COLOR 

This term refers to the hghter color of portions 
of cheese (p. 89). 

Cause : 

(1) The development of too much acid, which bleaches 

or renders paler the color of the curd. 

(2) Failure to firm the curd in the whey early enough. 

(3) Using large amounts of starter. 

(4) Using poor cheese-coloring. 

Prevention : 

(1) Have the curd firmed m the whey before the acidity 

has developed to more than 0.18 per cent. 

(2) Cheese should be colored to suit the market for which 

it is intended. 

Remedy : 

(1) The best place and time to produce a bright, even 

color m the curd is in the whey, while the whey is 
being removed. From the time the whey has 
reached the level of the curd till it is all removed, 
the curd should be well stirred. By watching the 
curd during this handling, the color can be seen to 
develop rapidly. This is due to the breaking of the 
film of moisture which surrounds each piece of curd. 

(2) Allow the curd to stand some time after salting befoie 

putting in press. 

MOTTLED COLOR 

This means an uneven color, most noticeable in 
colored cheese. 

129 



130 SCIENCE AND PRACTICE OF CHEESE-MAKING 

Cause : 

(1) An uneven development of acid and moisture in the 

curd. 

(2) Uneven cutting, leading to an uneven contraction of 

the curd when heated in the whey. 

(3) Neglecting to strain the starter when lumpy. 

(4) Adding the starter after adding the cheese-color. 

(5) Uneven piling and maturing of the curd 

(6) Use of poor cheese-color. 

(7) Mixing the curd from different vats. 

(8) Lumpy condition ot the curd at the time of removing 

the whey, or when salt is applied. 

(9) Adding old curd to fresh curd without proper pre- 

cautions. 
(10) Yeasts. When due to these, the mottling increases 
with the age of the cheese. 

Prevention : 

(1) By uniform cutting, heating and stirring. This is 

facilitated by the use of a 5-16-inch, perpendicular, 
wire knife, and a 5-8-inch, horizontal, steel knife. 

(2) Each small piece of curd should be kept separated from 

the others while being heated. 

(3) The starter should always be strained. 

(4) The starter should be added before the cheese-color 

is added. 

(5) The curd from different vats should not be mixed. 

(6) In using old curd, it should be placed in the vat about 

15 minutes before the whey is removed. 

(7) Curd should always be firmed in the whey before too 

much acid has developed. 

Remedy : 

When the curd is badly mottled, there is no remedy that 
will make the color uniform. In some instances the color 
will become more even as the cheese ages. Preven- 
tion is the best remedy. 

SEAMY COLOR 

This is a condition in which the outline of each 
piece of curd can be easily seen in the cheese. 
The uniting surfaces are marked by a pale Hne. 
(Fig- 3I-) 



DEFECTS IN COLOR AND FINISH 



131 



Cause : 

(1) Greasy curds, preventing even absorption of salt 

(2) Impure salt. 

Prevention : 

(1) If curds are very greasy, they should be rinsed ofl 

with water at 90° F. just before salting 

(2) Only high-grade salt should be used. 
Remedy : 

There is no satisfactory remedy. Prevention is the only 
sure way of overcoming the trouble. 




.»;>/^. -■'■?■».*■.- ■>■.■■.>■ ' ■ ■v' ^'t f- - ' ■^^■■\'.. ■-■" S!gV 










FIG. 31 — ILLUSTRATION OF SEAMY COLOR AND ALSO OF LACK 

OF PRESSING 



RUSTY SPOTS 

These are red spots resembling rust, and usually 
located in the little pockets of fat that are found 
where two pieces of curd come together in pressing. 
This is most noticeable in white cheese. 

Cause : 

(f) Bacillus ruiensis, gaining entrance to milk or curd. 
(2) Unsanitary buildings and surroundings. When whey 
leaks through the factory floor, the red material 



132 SCIENCE AND PRACTICE OF CHEESE-MAKING 

formed by these bacteria may develop. The in- 
fectious material may then be carried into the 
factory by wind or flies. Once in the factory, every 
utensil used in cheese-making soon becomes infected 
and the trouble constantly increases. 

Prevention : 

(1) Keep everything used in the factory absolutely clean. 

(2) Do not allow the factory floor to leak. Cement floors 

are the most sanitary. 

(3) Keep the drain and drain-pipes clean. 

(4) Use screen-doors and windows during fly time. 
Remedy : 

(1) The only way to get rid of this trouble is by a 

thorough cleaning and disinfection of the factory 
surroundings and of all utensils. 

(2) The starter, if one is used, should be renewed. 

METHOD OF CLEANING AND DISINFEC- 
TION 

(1) Wash all utensils with a brush, hot water, and wash- 

ing-powder, and put them into the large milk-vat. 

(2) Put a cover over the vat and turn live steam into it. 

(3) Steam the utensils for at least one-half hour. 

(4) If the drains are dirty, clean them with hot water 

and washing-powder. Then steam them for at least 
20 minutes. 

(5) If the ground, surrounding or under the factory, is 

infected, have it covered with lime or fresh earth. 

(6) The inside walls, cheese -shelves, and all wood-work 

should be washed with a hot solution of bichlorid 
of mercury (corrosive sublimate). This is made by 
dissolving 7 J grains of bichlorid of mercury in one 
pint of water. Handle this substance with care and 
apply this solution with a brush or broom, since it 
is a powerful poison. 

DEFECTS IN FINISH 

This includes anything that detracts from the ap- 
pearance of a cheese. As a rule, such defects are 
due to carelessness on the part of the cheese-maker. 



DEFECTS IN COLOR AND FINISH I33 

UNCLEAN SURFACES 
Cause : 

(1) Placing cheese on unclean or moldy shelves in the 

curing-room. 

(2) Using dirty hoops or handling the cheese with dirty 

hands. 

Prevention : 

(1) Wash the shelves after each shipment of cheese leaves 

the factory. Use a brush, hot water, and some good 
washing-powder that will remove grease. Place the 
shelves in the sunlight to dry. 

(2) Cheese-hoops should be clean. So should the hands 

of the maker. 

CRACKED RINDS 

These are openings in the side or ends of the cheese. 
They are unsightly and allow cheese-flies and molds 
to enter. 

Cause : 

(1) Too much acid. 

(2) Greasy curd. 

(3) Use of hard press-cloths. 

(4) Lack of pressing. 

(5) Wrinkled bandages. 

(6) Too dry an atmosphere in curing-room. 

Prevention : 

(1) Avoid excess of acid in making cheese (p. 53). 

(2) Rinse greasy curd with water at 90° F. before salting. 

(3) Press-cloths can be softened by soaking in a weak 

solution of sulphuric acid. 

(4) Press the cheese longer before dressing and have the 

bandages well pulled up. 

(5) The curing-room atmosphere should show 80 per cent 

humidity. 

Remedy : 

(1) Press the cheese again after washing with warm 

water. If this fails, 

(2) Paraffin the cheese. 



134 SCIENCE AND PRxVCTICE OF CHEESE-MAKING 

MOLDY SURFACES 

This condition is familiar. The formation may be 
of several colors. 

Cause : 

The growth of molds is due to 

(1) Too much moisture in the air. 

(2) Too high temperature. 

(3) Insufficient circulation of air. 

(4) Lack of cleanliness m curing-room. 

Prevention : 

(1) Curmg-rooms should be so equipped that the temper- 

ature and moisture can be controlled. 

(2) Good circulation of air should be provided. 

(3) Curing-rooms should be kept clean. 

Remedy : 

(1) By spraying cheese with formalin, containing 10 per 

cent of formaldehyd. 

(2) By burning sulphur, 3 pounds to 1 ,000 ctibic feet of air. 

(3) By washing the ceilings, walls, shelves and all wood- 

work with a hot solution of bichlorid of mercury, 
made by dissolving 7^ grains in a pint of water 
(p. 132). 

(4) By whitewashing the walls and ceilings 

UNEVEN SIZES 

CROOKED SIDES 

WRINKLED BANDAGES 

COLLARS ON PRESS ENDS 

All these are common defects in the finish of cheese. 

They are found in almost every factory. 

Cause : 

Such defects are nearly always due to carelessness on the 
part of the cheese-maker. The presses may be worn 
out or broken, the followers may not fit the hoops, or 
too heavy pressure may be applied immediately after 
dressing. 



DEFECTS IN COLOR AND FINISH 135 

Remedy : 

The only way by which defects m finish may be overcome 
is by proper care on the part of the cheese-maker. Very 
often cheese buyers pay less money for cheese of a good 
quality when it is poorly finished. If the cheese-maker 
has to pay the reclaim, he generally becomes more care- 
ful. There is no excuse for badly finished cheese, be- 
cause it is within the power of every cheese -maker to 
make cheese with good finish. A poorly finished cheese 
is a disgrace to the man who made it. 



Part III 

The 
Science of Cheese-Making: 

The Chemtcaly 

Biological and Other Relations 

of Milk and Cheese 



Relations of the Constituents of Milk to 
Cheese. 

Relations of Micro-Organisms and En- 
zyms to Milk and Cheese. 

Changes in Cheese During tne Ripening 
Process. 



137 



CHAPTER XIV 

The Constituents of MUk 

The following constituents of cow's milk are of 
special importance in cheese-making: 

(i) Fat 

(2) Casein 

(3) Milk-sugar 

(4) Salts 

(5) Enzyms 

If this list of milk constituents is compared with 
a complete statement of the composition of milk, it 
is noticeable that water and albumin are omitted. 
There are good reasons for such omission. 

So far as the process of cheese-making and the 
character of the product are concerned, the amount 
of water in normal milks requires no special con- 
sideration. Slight variations in conditions of the 
operations of cheese-making affect the percentage 
of water in cheese much more than the variation of 
the percentage of water in normal milks. While 
dilution of milk by water beyond a certain propor- 
tion decreases the rapidity and completeness of 
rennet action (p. 307), the amount of water in dif- 
ferent normal milks does not vary enough to exert 
any such retarding influence that is appreciable, so far 
as our observations go. 

Milk-albumin calls for little or no study in cheese- 
making, since it remains in solution during the 

139 



140 SCIENCE AND PRACTICE OF CHEESE-MAKING 

cheese-making process and passes out, for the most 
part, with the whey. Numerous attempts have been 
made to recover in cheese all or most of the albumin 
present in milk, but we know of no case which has 
resulted in making a product like normal cheddar 
cheese in its properties. 

MILK-FAT 

Milk-fat, also known as butter-fat, is not a single 
chemical compound, but is a somewhat variable 
mixture of several different compounds called 
glycerids. Each glycerid is formed by the chemical 
union of glycerin as a base with some organic acid 
or acids of a particular kind (butyric, palmitic, 
oleic, etc.). Under the action of certain kinds of 
micro-organisms, milk-fat undergoes decomposi- 
tion, forming among other products free butyric acid, 
which is the compound responsible for the offensive 
flavor of rancid cheese and butter. 

Fat-globules in milk. — Milk-fat is present in milk, 
not in solution, but suspended in the form of very 
small, transparent globules. The globules vary in 
size, the smaller being more numerous than the 
larger ones. The average size of fat-globules in 
milk is somewhat larger than one ten-thousandth 
of an inch in diameter. Contrary to what has been 
formerly taught, the fat-globules of milk have no 
special kind of covering, but are simply minute 
particles of fat, floating free in milk in the form of 
an emulsion. Skim-milk and whey contain few 
globules, as compared with normal milk, while 
cieam, of course, contains many more than normal 



CONSTITUENTS OF MILK I4I 

milk. Even in butter and cheese, the fat-globules 
of the milk preserve their individuality to a large 
extent. 

MILK-CASEIN 

Milk-casein is of special importance in connection 
with cheese-making because the conversion of milk 
into cheese is dependent upon the peculiar proper- 
ties of casein. This constituent of milk, in an im- 
pure and changed form, is most commonly familiar 
as the solid, white substance, called curd, which forms 
in milk when it sours. It is also familiar as a prom- 
inent constituent of separator-slime, and in this form 
is not materially changed from the condition in which 
it exists in milk. 

Composition of milk-casein. — Casein, as it exists 
in milk, is a very complex chemical compound, be- 
longing to a general class of nitrogen-containing com- 
pounds known as protein, and to a special subdivision 
called phosphoprotcins. Its elementary composition is 
about as follows . 

Carbon 53-00 P^i* cent 

Oxygen 22.70 per cent 

Nitrogen i5-70 per cent 

Hydrogen 7.00 per cent 

Phosphorus 0.85 per cent 

Sulphur 0.75 per cent 

The presence of phosphorus in casein is one of 
its distinguishing chemical features, but in what 
particular form of combination the phosphorus ex- 
ists is not known at present. Casein in milk does 



142 SCIENCE AND PRACTICE OF CHEESE-MAKING 

not exist as an uncombined protein, but is, accord- 
ing to the best evidence available, in combination 
with some form of calcium. Three general views 
have been held in regard to the relation of calcium 
(lime) compounds to milk-casein: (i) That 
milk-casein is in the form of calcium casein, being 
combined with about 1.50 per cent of calcium oxid; 
(2) that casein is combined directly with calcium 
phosphate ; ( 3 ) that the compound calcium casein 
is also in combination with calcium phosphate. 
Some facts appear to indicate that the calcium 
casein of milk is a form containing 2.4 per cent of 
calcium oxid. It has been well established that 
casein forms compounds with calcivmi, but which 
particular form of combination exists in milk, as 
milk-casein, we cannot yet regard as settled beyond 
question. 

Physical condition of casein in milk. — For a long 
time casein was believed to be in solution in milk 
and is still held to be so by those who have ignored 
the evidence to the contrary. Some have held that 
it was in a state of semi-solution. The view which 
must now be regarded as representing the truth be- 
yond all doubt is that casein exists in milk in the 
form of extremely minute, gelatinous particles in 
suspension. The evidence which proves the cor- 
rectness of this view is threefold: (i) While the 
solid particles of casein are so small that they easily 
pass through the pores of fine filter-paper, they do 
not go through the finer pores of unglazed porcelain 
(like the Chamberland filter) nor through animal 
membranes. It is thus possible to strain out casein 
from the soluble portions of the milk in quantities 



CONSTITUENTS OF MILK I43 

sufficient to see and examine. (2) Casein is sepa- 
rated from milk by centrifugal force, being de- 
posited as a film on the surrounding walls of the 
centrifuge. By whirling milk for a number of 
hours, practically all of the casein can thus be sepa- 
rated from the milk. It is thus that it is deposited 
on the walls of the bowl of a centrifugal separator 
as separator-slime, in which the casein, in a gelat- 
inous form, is mixed with dirt and other bodies. 
(3) These two preceding methods of proofs should 
be sufficiently convincing in regard to the insoluble 
condition of casein in milk; but the latest method 
removes all possibility of doubt. Within the past 
few months, an article has been published by 
Kreidl and Neumann, of Vienna, giving results of 
work done by them in studying milk by what is known 
as *'ultramicroscopic" examination. This method en- 
ables one to see very much smaller objects than can 
be seen by the usual methods of microscopic work. 
These investigators were able to see the actual par- 
ticles of casein swimming in milk, to treat them with 
reagents and to observe their various transformations. 
Their study included the milk not only of cows, but 
of other animals. 

Action of acids upon milk-casein. — Milk-casein is 
made to appear in milk as a heavy, white solid or 
precipitate, in more or less flocculent form, by means 
of dilute acids, even by carbon dioxid under certain 
conditions, and also by acid salts. Treatment by 
acids changes the chemical and physical properties 
of milk-casein. The most obvious change is that 
of physical condition, the very minute, invisible 



144 SCIENCE AND PRACTICE OF CHEESE-MAKING 

particles of casein coming together into large, vis- 
ible aggregations. The cause of this change cannot 
yet be fully explained. It has been usually ex- 
plained by saying that acids unite with the calcium 
of the calcium casein, and the casein, thus deprived 
of its combined calcium, is changed from its con- 
dition of finely divided, gelatinous particles into 
larger masses and then appears as a solid, heavy 
precipitate. This explanation is not entirely satis- 
factory, since casein may be obtained in the form of 
a precipitate when little or no acid is present. The 
effect is probably to be ascribed rather to the forma- 
tion of soluble calcium salts by the acid than entirely 
to the direct effect of acid upon the calcium of milk- 
casein. 

When milk sours in the ordinary way, the lactic 
acid, thus formed, acts upon the calcium casein, 
two definite changes taking place when sufficient acid 
is present. First, the lactic acid combines with the 
calcium of the calcium casein, forming calcium 
lactate and calcium-free casein (casein set free from 
its combination with calcium). When more lactic 
acid forms than is sufficient to combine with the 
calcium, the second change takes place; the free 
casein or coagulum takes up the acid, forming a 
mixture which is familiar as the curd of sour milk. 
It was formerly believed that insoluble, precipitated 
casein combines with a definite quantity of acid, 
forming a definite compound ; and that, under this 
supposition, the curd of sour milk is a compound 
known as casein lactate. But more extended, care- 
ful, and accurate work has shown that the evidence 
was misleading upon which was based the belief 



CONSTITUENTS OF MILK I45 

that casein unites with definite quantities of acids 
to form definite, insoluble compounds. Changes 
similar to those occurring when milk sours in the 
usual way take place when milk is treated with 
other acids, such as hydrochloric, acetic, sulphuric, 
etc. 

Free casein is insoluble in water, and also in very 
dilute acids at ordinary temperatures. The action 
of acids on calcium casein and on free casein is 
hastened by increase of temperature. Less acid is 
required at higher temperature to precipitate casein. 
Casein dissolves easily even in quite dilute acids, 
more easily at higher temperatures, forming soluble 
compounds which are either combinations of acid 
with casein or decomposition products of casein, 
according to the concentration of the acid, the tem- 
perature and other conditions of treatment. 

Action of alkalis on milk-casein. — Casein is acid 
in character in that it unites easily with fixed 
alkalis, ammonia and alkaline carbonates, forming 
salts easily soluble in water. Thus, the curd 
of sour milk or fresh cheese can be dissolved by 
treatment with dilute sodium carbonate or am- 
monia. This fact is made use of in cooking, when 
tough, insoluble cheese, such as that often made 
from skim-milk, is rendered more easily soluble by 
use of baking-soda. An interesting experiment in 
this connection is to rub in a mortar some pure 
casein, suspended in water, with some calcium car- 
bonate. The calcium combines with the casein, and 
carbon dioxid gas is given of¥. The soluble com- 
pounds of casein with alkalis are not curdled by 
rennet, but are precipitated on treatment with acids. 



146 SCIENCE AND PRACTICE OF CHEESE-MAKING 

Some of these salts formed by casein with alkalis 
are found in commerce in the form of dietetic and 
medicinal preparations. 

Action of salts on milk-casein. — Milk-casein may- 
be precipitated, apparently unchanged chemically, 
by saturating milk with common salt, magnesium 
sulphate, ammonium sulphate, etc., at ordinary tem- 
peratures. Milk-casein is also precipitated by small 
amounts of solution of alum, zinc sulphate and 
many other metallic salts. Calcium chlorid and 
some other salts coagulate casein in milk heated to 
95°-ii3° F. 

Action of heat on milk-casein. — Heat alone under 
ordinary conditions, even at the boiling point of 
water, does not coagulate the casein in milk. How- 
ever, heated under pressure to 26^° -28^° F., casein 
salts are changed in their properties and casein itself 
is coagulated. The browning of milk heated under 
pressure is more or less due to changes in casein. 
The formation of a peculiar skin (haptogen mem- 
brane) on milk heated above 140° F. is largely due 
to the calcium casein of the milk and not, as was 
formerly supposed, to albumin. The skin itself 
contains practically all of the constitutents of the 
milk and may be regarded as a kind of evaporated 
milk. On removing the membrane, a new layer is 
formed and, by removing these one after another, 
practically all of the milk can be transformed into 
the membrane condition. It appears to be due to 
surface evaporation. 

Action of rennet on milk-casein. — One of the 
most characteristic properties of milk-casein is its 
coagulation by the enzym or chemical ferment con- 



CONSTITUENTS OF MILK I47 

tained in rennet. This property makes possible 
the manufacture of cheddar and many other kinds 
of cheese from milk. The curd formed by the action 
of rennet is called paracasein or, more properly, cal- 
cium paracasein. The coagulation of milk-casein pro- 
duced by rennet is quite different from that produced 
by acids. Calcium paracasein behaves, in general, 
much like casein toward acids and alkalis. The details 
of rennet action on milk-casein will be considered more 
fully in Chapter XXII (p. 299). 

Other changes caused in milk-casein. — Under the 
action of chemical reagents, of enzyms and of various 
micro-organisms, calcium casein and paracasein 
may be changed into a large number of other sub- 
stances. Among the compounds and classes of com- 
pounds thus formed are caseoses (albumoses), 
peptones, amino acids (crystallizable bodies) and 
ammonia. These products are never found in nor- 
mal milk as it leaves the cow's udder, but may be 
present in milk that has stood exposed to air for some 
time. 

Brine-soluble substance formed from casein. — 
When milk is treated with rennet and the curd 
is handled in the usual manner followed in cheese- 
making, a most interesting change begins to take 
place, which becomes especially prominent in the 
cheddaring operation (p. 32). The curd changes 
into a form which is soluble in a warm solution of 5 
per cent brine (common salt) ; at the same time, the 
curd forms long strings on a hot iron and acquires the 
peculiar texture of the cooked meat of a chicken's 
breast, with a characteristic velvety mellowness of feel- 
ing and glistening, silky appearance. These changes 



148 SCIENCE AND PRACTICE OF CHEESE-AIAKING 

are due, apparently, to the formation of this brine- 
soluble substance. More or less of this peculiar 
substance remains in the cheese indefinitely. For 
example, in a cheese two-and-one-half years old, 
the portion of the cheese insoluble in ether (fat) 
and in warm water consisted entirely of this brine- 
soluble substance. On being warmed, it could be 
drawn out in strings over a yard long. (Figs. 32 
and 3S.) 





FIG. 32 — BRINE-S L U B L E FIG. 33 — STRINGS OF BRINE- 
CHEESE PROTEIN WARMED SOLUBLE PROTEIN OF 
AND FRESHLY DRAWN CHEESE SUSPENDED AND 
OUT IN A STRING SEV- DRIED. STRINGS ABOUT 
ERAL FEET LONG FOUR FEET LONG 

MILK-SUGAR 

Milk-sugar, also called lactose, is present in cow's 
milk in solution. In general composition, it re- 
sembles ordinary sugar, but it is less sweet and 
less soluble in water; however, it differs much from 



CONSTITUENTS OF MILK I49 

ordinary sugar in its chemical behavior and espe- 
cially in its relations to various ferments. The 
amount of sugar in milk varies from below 4 to 
over 6 per cent and averages about 5 per cent. 
Variation in the amount of sugar in different nor- 
mal milks has little interest in connection with the 
operations of cheese-making for the reason that 
there is always an abundance for cheese-making 
purposes. The milk-sugar passes largely into the 
whey in the cheese-making process and forms a 
large percentage of the solids in whey. The milk- 
sugar of commerce is usually prepared by evaporat- 
ing whey and purifying the impure product first 
obtained. The importance of milk-sugar in cheese- 
making depends on the fact that it is easily con- 
verted into lactic acid by certain forms of bacteria. 
In the making of cheddar cheese, only a small pro- 
portion of the sugar is changed into lactic acid during 
a considerable part of the process, but one per cent or 
more is so changed by the time the curd is salted. In 
cheese made from sour milk, such as cottage cheese, 
and in starters used in cheese-making, somewhat 
more than one-fourth of the milk-sugar is changed 
and there is formed in such cases about 0.7 or 0.8 
per cent of lactic acid. When milk or whey is 
allowed to stand for some time at ordinary tem- 
peratures, over I per cent of lactic acid may 
be formed. Hence, sour milk or whey, when two 
or three days old, usually contains only 3.5 to 4 
per cent of milk-sugar. In cheddar cheese made 
under normal conditions, we never find any un- 
combined or free lactic acid, since it combines with 
calcium of certain calcium salts in the milk to form 



150 SCIENCE AND PRACTICE OF CHEESE-MAKING 

calcium lactate, a compound which is neutral 
(neither acid nor alkaline), and which does not 
taste sour. Under the usual forms of fermentation, 
milk-sugar forms small amounts of other com- 
pounds in addition to lactic acid. The sour smell 
of whey and of sour milk is not due to free lactic 
acid, since pure lactic acid has practically no odor, 
but is caused by some of the other fermentation 
products formed, the exact nature of which is not 
fully known. 

THE SALTS OF MILK 

The salts of milk, commonly represented by the 
term **ash," are present in only small amounts, but 
they have extremely important relations to the 
process of cheese-making. Our knowledge of these 
compounds is very incomplete. The salts of milk 
are commonly spoken of as the ash or mineral con- 
stituents. This conception is somewhat misleading, 
because the materials appearing in the ash of milk 
are, to some considerable extent, combined in or- 
ganic compounds, instead of existing in milk as 
separate inorganic bodies in the form in which they 
appear in the ash. The ash, therefore, represents 
in amount more than the so-called mineral con- 
stituents of milk and less than the salts of milk. 
While the average amount of ash in milk is about 
0.7 per cent, the amount of salts is probably much 
nearer 0.9 per cent. To illustrate this point in more 
detail, the citric acid which is present in milk in 
the form of citrate salts does not appear at all 
in the ash, since it is destroyed in burning the milk, 
to obtain the ash. In cheddar cheese the ash not 



CONSTITUENTS OF MILK: I5I 

Including the salt added in cheese-making, rep- 
resents the salts of the milk even less accurately 
than in milk. In cheese, we have a considerable 
amount of calcium lactate, but, in obtaining the ash 
of cheese, the lactic acid portion is destroyed and so 
does not form a part of the ash. ▼The percentage 
of ash in green cheese due to constituents obtained 
from the milk is usually between 2 and 3 per cent, 
varying, of course, with the amount of whey retained 
in the cheese. 

In milk, a portion of the salts is present in 
soluble, and a portion in insoluble, form. The fol- 
lowing portions of the salts of milk are present in 
solution : Sodium, potassium, chlorine, and citric 
acid compounds ; amounts of phosphoric acid in 
the form of combined phosphates varying in differ- 
ent milks from 45 to 65 per cent of the total phos- 
phoric acid present; 25 to 45 per cent of the calcium 
(lime) ; and over 50 per cent of the magnesium. 
In what specific forms of compounds these ele- 
ments are present in milk is not known and the 
problem is a difficult one to solve. The sugges- 
tion has been made by Soldner that something like 
the following arrangement may be supposed to 
exist : 

Percentage of the total 
Compounds salts in milk 

Calcium citrate 23.6 

Mono-potassium phosphate 12 .8 

Sodium chlorid 10.6 

Potassium chlorid 9.2 

Di-potassium phosphate 9.2 

Tii-calcium phosphate 8.9 

Di-calcium phosphate 7 .4 

Potassium citrate 5.5 

Calcium oxid in casein 5.1 

Magnesium citrate 4.0 

Di-magnesium phosphate 3.7 



152 SCIENCE AND PRACTICE OF CHEESE-MAKING 

Whether this suggested distribution of com- 
pounds among the salts of milk is near the truth 
or not, it emphasizes the fact that the matter is 
one of no little complication. Some investigators 
believe that the calcium phosphate exists entirely as 
tri-calcium phosphate ; others, as the di-calcium com- 
pound, probably on the basis of better evidence. The 
presence of soluble acid phosphate and, probably, of 
acid citrate also, accounts for a part of the acidity of 
fresh milk. 

When milk is heated, the amount of soluble calcium 
salts is decreased as the result of being changed to 
insoluble forms. 

The presence of soluble calcium salts in milk is 
essential to the coagulation of milk by rennet-extract 
(p. 306). 

Acidity of milk. — In this connection, we will call 
attention to the acidity of fresh, normal milk. Milk 
in which lactic acid has had no chance to develop has 
the power of neutralizing alkalis and in that respect 
behaves like a solution containing acid. 

The acidity of fresh milk varies with a number of 
conditions, such as ( i ) the milk of the same ani- 
mal at different times, (2) the milk of different 
cows, and (3) with the stage of lactation, being 
highest at the beginning of lactation and gradually 
decreasing with the advance of the lactation period. 
The acidity ot fresh normal milk is caused by no 
one substance, but is due to the presence of ( i ) 
acid phosphates, (2) citrates and (3) casein. It 
has been found to vary widely, from below 4 to over 
10, expressed as cubic centimeters of one-tenth 
normal alkali, but in most cases it is between 7 
and 9. 



CONSTITUENTS OF MILK 153 

Lactic acid begins to be formed in milk soon 
ifter it is drawn, if the milk is not kept below 50° 
F. By the time milk reaches the factory, the nor- 
mal acidity of the milk is usually increased about 
0.05 to o.io per cent, corresponding to a total 
acidity of 0.12 to 0.18 per cent. In warm weather, 
the acidity often exceeds 0.20 per cent in the case of 
some herds. The increase of acidity over that ex- 
isting in fresh normal milk is an indication of the 
temperature at which the milk is kept and also of 
the cleanliness observed in milking and in caring for 
the milk and the dairy utensils with which the milk 
comes in contact (see p. 4). An acidity equivalent 
to 0.20 per cent of lactic acid in milk when received 
at the factory is regarded as the danger line for Ched- 
dar cheese-making. Generally, only a part of the 
milk taken to a cheese-factory will exceed this limit, 
so that the average for the day may be considerably 
below the 0.20 per cent limit. 

MILK— ENZYMS 

Enzyms are chemical ferments ; they have the 
power to produce changes in other substances with- 
out themselves undergoing change. Enzyms are 
the products of living cells. According to recent 
views, normal milk is not to be regarded as an in- 
active fluid, but possesses certain properties char- 
acteristic of living substances. Normal milk gives 
evidence of the presence of several different en- 
zyms, among which are those called (i) diastase, 
(2) galactase, (3) lipase, (4) catalase, (5) peroxi- 
dase and (6) reductase. The subject has not been 
sufficiently studied to enable one to make anything 



154 SCIENCE AND PRACTICE OF CHEESE-MAKING 

like a clear or satisfactory presentation. It is quite 
probable that some of these enzyms, now described 
under different names, are the same or are mix- 
tures. The quantity of these substances is so ex- 
tremely small and the methods of separating them 
in pure form are so imperfect that their study pre- 
sents peculiar difficulties. One of the main prac- 
tical uses to which enzyms in milk have been put 
depends upon the fact that their presence serves to 
distinguish unheated from boiled milk, because the 
enzyms are all destroyed by heat. We shall not 
consider these substances in detail because, so far 
as we now know, most of them are not concerned 
in cheese-making. Galactase is the only one of special 
interest in this connection. This was discovered at 
the Wisconsin experiment station in 1897 and has 
received considerable attention in connection with 
studies of milk and cheese. We shall consider this 
enzym in more detail later (p. 297). 



CHAPTER XV 

Conditions Affecting Proportions of 
Constituents in Milk 

In studying the composition of milk from dif- 
ferent cows or herds, one of the first facts noticed 
is that the same constituents vary in amount more 
or less widely in dififerent milks. . This fact is of 
the highest importance in studying the relations 
of milk to cheese-making. As a foundation for 
a more detailed consideration of these relations of 
milk, it seems desirable that we should study with 
some degree of fullness the more important condi- 
tions which cause variation in the amounts of 
constituents of milk. Those constituents of great- 
est interest to us which vary most are fat and 
casein. Milk-sugar and salts vary only slightly 
as compared with the amount of variation in fat 
and casein. We shall find it to be a matter, not 
only of interest, but of practical importance, to study 
the extent of these variations and their causes, 
and also to learn to what extent dififerent influences 
affect the relation of fat to casein. As we shall 
show later (p. i86), the percentages of fat and 
casein in milk largely determine the yield of cheese; 
while the proportion of these two constituents, relative 
to each other, determine the composition (p. 231) 
and to a considerable degree, the quality of cheese 
(P- 243). 

155 



156 SCIENCE AND PRACTICE OF CHEESE-MAKING 

AMOUNT OF FAT IN MILK 

The percentage of fat in normal milk varies 
greatly, much more than any other constituent, 
especially if we consider single milkings of individ- 
ual cows. In connection with the manufacture of 
cheese, we are more particularly interested in 
knowing the percentage of fat in the milk of dif- 
ferent herds of cows rather than in that of single indi- 
viduals. In the case of single herds of cows, such 
as are common in the dairy region of New York 
state, the lowest percentage of fat found on any 
one day, as the result of special investigations, 
was 2.90; the highest, 5.50, v/hich occurred late in 
the season (October). Taking the average of dif- 
ferent herds of cows for an entire cheese-factory 
season (April to November), the lowest percentage 
of fat was 3.31 and the highest, 4.31. In the case 
of cheese-factory milk, consisting of a mixture of 
the milk of different herds, the lowest percentage 
of fat found was 3.04 and the highest, 4.60. The 
average percentage of fat in mixed factory milk 
for an entire season is about 3.75 ; and this average 
has been found to vary only slightly in different 
factories and in different seasons. The Wisconsin 
experiment station reports 3.64 as the season's 
average percentage of fat in the milk of 347 fac- 
tories. In the case of individual factories, a sea- 
son's average as low as 3,20 per cent is given. The 
lowest percentage of fat in the milk of any single 
herd for a single day's milk is given as 2.30, while 
the highest reported is 5. Results reported in Can- 
ada appear to indicate a lower percentage of fat in 
milk than in the case of New York. 



VARIATIONS OF MILK CONSTITUENTS 1 57 

While many conditions cause the percentage of fat 
in milk to vary, we will notice only three as of special 
importance in connection with cheese-making: (i) 
Breed, (2) stage of lactation, and (3) change from 
barn to pasture. 

Influence of breed of cows on fat content of milk. 

— The influence of what is known as breed upon 
the composition of cow's milk has been long recog- 
nized and extensively studied in a general way, 
but only in a comparatively limited way in its rela- 
tion to cheese-making. It is largely owing to this 
influence that we find the milk of one country dif- 
fering from that of another, or the milk of one 
section of a country differing from that of another 
section. For example, the average percentage of 
fat in milk in Germany and Holland is fully one- 
half per cent lower than in New York state, and 
probably in the United States at large, because the 
prevailing breeds of cows there are those producmg 
milk comparatively low in fat. The results of 
recent tests go to show that in Canada the milk 
in Quebec province contains more fat than does 
that of Ontario, since in the former the native 
Jerseys are the predominant breed, while in the 
latter, Holstein-Friesians, Ayrshires and Short- 

PERCENTAGE OF FAT IN MILK OF DIFFERENT BREEDS OF 

cows 

Name of breed Per cent of fat in milk 

Holstein-Friesian 3.26 

Ayrshire 3.76 

American Holderness 4.01 

Shorthorn 4.28 

Devon 4.89 

Guernsey ^-38 

Jersey 5.78 



158 SCIENCE AND PRACTICE OF CHEESE-MAKING 

horns prevail. The foregoing table represents aver- 
ages in the case of three to six individuals of each 
of seven different breeds for an aggregate of four 
to twenty lactation periods with each. 

Influence of stage of lactation on fat content of 
milk. — From the time a cow "comes fresh in milk" 
up to the time she becomes "dry," the composition 
of the milk undergoes gradual changes, which are 
quite independent of other factors. The period of 
lactation varies in length with different individual 
cows, but, for practical purposes, lasts about 10 to 
12 months. The changes observed in the percent- 
age of fat during the progress of the lactation 
period are quite marked and fairly regular, with- 
out reference to individual or breed. The colos- 
trum, which is the secretion produced by a cow 
soon after calving, is very different in composition 
from normal milk and is not considered at all in 
our discussion of the constituents of milk, because 
it has no interest for us in this connection. The 



VARIATION OF PERCENTAGE OF FAT IN MILK WITH 
ADVANCE OF LACTATION 



Month of lactation 


Per cent of 
fat in milk 


Percentages in 

comparison with 

first month 


1 


4.30 
4.11 
4.21 
4.25 
4.38 
4.53 
4.57 
4.59 
4.67 
4.90 
5.07 


100 


2 


95 6 


3. . 




97 9 


4 


98 8 


5 


101 9 


6 


105 3 


7 


106 3 


8 


106 8 


9 


108 6 


10.. 




1 14 


11... 





118 








VARIATIONS OF MILK CONSTITUENTS 



159 



figures presented in the table on page 158 represent 
the monthly averages of nearly 100 different lactation 
periods. 

In studying this table, we notice that the per- 
centage of fat decreases in the second month, as 
compared with the first, and then begins to in- 
crease, continuing to increase from month to month 
during the entire period of lactation. The rate of 
increase is more rapid during the last two or three 
months than previously. Such behavior appears 
to be the general rule. Variation from the com- 
parative degree of regularity observed in the fore- 
going table may, of course, appear in the case of 
individuals. 

It will be a matter of more immediate interest to 
consider the influence of advancing lactation upon the 
percentage of fat as observed in the case of milk 
used at cheese-factories. In general, dairymen 
have their cows begin the period of lactation in 
March and April, so that milk taken to a cheese- 
factory represents, during the season, stages of the 
lactation period extending from about the second 

VARIATION OF FAT IN CHEESE-FACTORY MILK WITH 
ADVANCE OF LACTATION 



Month 



April 

May 

June 

July 

August. . . 
September 
October. . . 



Per cent of fat 
in milk 



New York 
3.43 
3.58 
3.64 
3.62 
3.84 
3.98 
4.23 



Wisconsin 
3.48 
3.49 
3.50 
3.55 
3.63 
3.84 
4.08 



Percentages in com- 
parison with first nionth 



New York 
100.0 
104.4 
106.1 
105.5 
112.0 
116.0 
123.3 



Wisconsin 
100.0 
100.3 
100.6 
102.0 
104.3 
110.3 
117.2 



l60 SCIENCE AND PRACTICE OF CHEESE-MAKING 

to the eighth months. Cows kept under ordinary- 
farm conditions are subject to greater variations 
of external influences than those used in the investi- 
gation represented by the figures in the preceding 
table. The figures in the table on page 159 repre- 
sent results secured in New York and Wisconsin. 

Influence of change from barn to pasture upon 
the percentage of fat in milk. — In the course of a 
study of cheese-factory milk in New York, it was 
noticed that, under certain conditions, a marked 
change in percentage of fat in milk took place. 
Each year while the study of factory milk was carried 
on, it was observed that about the middle of May 
there was a considerable increase in the percentage 
of milk-fat, accompanied by an increase of other 
solids and also by a larger yield of milk. Thus, 
during the first half of May, the milk contained 
3.46 per cent of fat and, during the second half, 
3.70 per cent. These results are in agreement with 
those reported by the Vermont and Wisconsin ex- 
periment stations and also by the Ontario agricul- 
tural college. This question has been more thor- 
oughly studied at the Vermont experiment station 
than elsewhere and, according to the results ob- 
tained during a series of years, the general rule 
shows a change like that noticed above, but in some 
years little or no change could be observed. A 
careful study of all the available facts appears to 
justify the explanation that the increased per- 
centage of fat in milk under the given circum- 
stances was due to a marked change in the char- 
acter of the food and environment of the cows, 
since they were turned out to pasture about the 



VARIATIONS OF MILK CONSTITUENTS l6l 

middle of May. Under the known existing condi- 
tions of the food and environment of cheese-factory 
cows, there was thus a change from dry food of 
an indifferent character, mainly straw or poor hay 
without grain, to a highly succulent food of a most 
palatable kind. It is probable also that the changes 
in the environment of the cows from confinement 
in barn and yard to the freedom of pasture exercised 
a beneficial, physiological influence. 

AMOUNT OF CASEIN IN MILK 

The percentage of casein in normal milk varies 
quite widely, though much less than in case of 
milk-fat. In the single milkings of individual cows, 
we have found casein as low as 1.59 per cent and 
as high as 4.49 per cent. The highest percentages 
were found in the case of cows far along in lacta- 
tion and giving only small amounts of milk. In 
the case of individual herds of cows, the percentage 
of casein ranged from 1.79 to 3.02. In the case of 
milk consisting of a mixture of the milk of several 
different herds, the percentage of casein varied from 
1.93 to 3.00. 

The conditions which influence variation of casein 
in milk, so far as they are of special interest to us 
here, are (i) breed, (2) stage of lactation, (3) 
change from stable to pasture, and (4) effects of 
drouth. 

Influence of breed of cows on percentage of 
casein in milk. — The following results illustrate, in 
general, the variation of casein in the milk of different 
breeds of cows : 



I02 SCIENCE AND PRACTICE OF CHEESE-MAKING 

PERCENTAGE OF CASEIN IN MILK OF DIFFERENT BREEDS 

OF COWS 

Name of breed Per cent of casein in milk 

Holstein-Friesian 2.20 

Ayrshire 2 .46 

American Holderness 2.63 

Shorthorn 2.79 

Devon 3.10 

Guernsey 2.91 

Jersey 3.03 

Influence of stage of lactation on the percentage 
of casein in milk. — We will first present results 
representing the average of about lOO lactation periods 
of individual cows and then the results representing 
work done at the New York experiment station in 
connection with cheese-factories in New York state, 
already referred to : 

VARIATION OF PERCENTAGE OF CASEIN IN MILK WITH 
ADVANCE OF LACTATION 





Month of lactation 


Per cent of 


Percentapres in compari- 






casein in milk 


son with first month 


1.. 




2.54 


100.0 


2.. 




2.42 


95.3 


3.. 




2.46 


96.8 


4.. 




2.52 


99.2 


5.. 




2.61 


102.8 


6.. 




2.68 


105.8 


7.. 




2.74 


108.0 


8.. 




2.80 


110.2 


9.. 




2.90 


114.2 


10.. 




3.01 
3.13 


118.5 


11 


123.2 



According to these results, the percentage of casein 
decreases in the second month of lactation, as com- 
pared with the first, and then begins to increase, con- 
tinuing to increase month by month to the end of the 
lactation period. The behavior very closely resembles 
that of fat. 



VARIATIONS OF MILK CONSTITUENTS 



163 



Turning now to the results obtained at cheese-fac- 
tories, we have the following data : 

VARIATION OF CASEIN IN CHEESE-FACTORY MILK WITH 
ADVANCE OF LACTATION 



Month 



April 

May 

June 

July 

August . . . . 
September, 
October. . . 




Percentag-es in compari- 
son with first month 



100.0 
102.2 
108.0 
106.1 
104.3 
111.3 
122.7 



In the foregoing figures, we see that the percentage 
of casein in milk increases in May and still more in 
June, after which a decrease takes place in July, fol- 
lowed by still further decrease in August. There is a 
rapid recovery and advance during September and 
October. The cause of these variations will be con- 
sidered later. 

Influence of change from barn to pasture upon 
the percentage of casein. — Attention has already 
been called to this subject in relation to fat. We now 
give corresponding figures for casein. During the 
first half of May, the milk contained 2.25 per cent of 
casein and during the second half of May, 2.45 per 
cent. The same explanation applies as in the case 
of increase of fat. 

Influence of drouth upon the percentage of casein 
in milk. — During a time of severe drouth in New 
York, beginning in July and lasting through Au- 
gust, with infrequent and insufficient showers, a 
marked decrease was noticed in the casein of the 
milk, even when the fat was increasing. The ana- 



1 64 SCIENCE AND PRACTICE OF CHEESE-MAKINC 

lytical data are given later on p. i68. Under these 
conditions, the pasture grasses were badly burned, 
most of the dairymen were without supplementary 
supplies of food, and consequently the cows suf- 
fered a certain degree of starvation. The changes 
in composition of milk were accompanied by a 
severe shrinkage in yield of milk. Along with this 
impaired condition of food supply, the animals 
were subjected to the unfavorable effects coming 
from excessive heat combined with annoyance of 
flies. Cheese-makers often complain of the be- 
havior of the cheese made at such times, without 
understanding the cause of their difficulty. The 
cheese leaks fat badly, does not press together well, 
and does not stand up perfectly, although behaving 
properly when first made. There is also noticed 
an excessive loss of fat in whey. This behavior is 
due to an abnormal decrease of casein in relation 
to fat, so that the milk and cheese contain an ex- 
cess of fat. Cheese-makers at such times are really 
dealing with milk which is not normal factory milk, 
but which is like normal factory milk to which some 
cream has been added. The extreme heat of the 
weather, which causes the decrease of casein, also 
makes it more difficult to handle such milk in cheese- 
making. In the twelfth annual report of the Wiscon- 
sin experiment station, attention is called to a similar 
condition. 

RELATION OF FAT AND CASEIN IN MILK 

As we shall see later (p. 231), the relation of 
fat and casein in milk is an extremely important 
one in connection with cheese-making. At this 



VARIATIONS OF AIILK CONSTITUENTS 



it)5 



point we shall call attention only to the general 
relation in different milks and to the conditions 
which influence this relation, leaving the various 
application of the facts to later chapters. We have 
already noticed the percentages of fat and of casein 
in milk and some of the conditions which cause 
variation. We now come to consider whether fat 
and casein vary alike ; that is, whether fat and casein 
have the same relation to each other in milk under 
all conditions. We will consider this phase of the 
subject under the following divisions: (i) Individ- 
uality, (2) breed, (3) stage of lactation, and (4) fresh 
pastures and drouth. 

Influence of individuality upon relation of fat 
and casein. — The results of the work done at the 
New York experiment station and elsewhere have 
shown that the relation of fat and casein varies greatly 
in the milk of different individuals, the variation being 
greatest, of course, in the case of single milk- 
ings. This fact has been well recognized for 15 
years or more and is too .familiar even to need illus- 
tration. 

Influence of breed upon relation of fat and 
casein. — The following data are taken from those 
already given on preceding pages. 



Name of breed 


Per cent 
of fat 


Per cent 
of casein 


Parts of casein for 
one part of fat 


Holstein-Friesian 


3.26 
3.76 
4.01 
4.28 
4.89 
5.38 
5.78 


2.20 
2.46 
2.63 
2.79 
3.10 
2.91 
3.03 


Fat: Casein 
1: 0.67 


Ayrshire 

American Holdemess 


1: 0.65 
1: 0.66 


Shorthorn 

Devon 

Guernsey 

Jersey 


1: 0.65 
1: 0.63 
1: 0.54 
1: 0.52 



l65 SCIEXCE AND PRACTICE OF CHEESE-MAKING 

It is seen that the different breeds represented 
separate into two general groups in relation to the 
ratio of fat to casein. In the case of the first five 
breeds in the list, this ratio does not vary widely. 
The milk containing least fat contains the largest 
amount of casein in relation to fat ; but, even though 
the percentage of fat in the case of this group in- 
creases to 4.89, as in the case of the Devon breed, 
the ratio of casein does not diminish greatly. The 
Guernsey and Jersey breeds constitute the second 
group, the fat being high in amount but the casein 
relatively low. 

Influence of stage of lactation upon the relation 
of fat and casein. — We have already noticed that 
the percentage of fat and of casein increases grad- 
ually and quite regularly during the period of lacta- 
tion. We will now consider the question as to 
whether these constituents increase in the same 
ratio. 

RELATION OF FAT AND CASEIN DURING LACTATION 

PERIOD 





Per cent 


Per cent 


Parts of casein for 


Month of lactation 


of fat 


of casein 


one part of fat 








Fat: Casein 


1 


4.30 


2.54 


1: 0.59 


2 


4.11 


2.42 


1: 0.59 


3 


4.21 


2.46 


1: 0.58 


4 


4.25 


2.52 


1: 0.59 


5 


4.38 


2.61 


1: 0.60 


6 


4.53 


2.68 


1: 0.59 


7 


4.57 


2.74 


1: 0.60 


8 


4.59 
4.67 


2.84 
2.90 


1: 0.61 


9 


1: 0.62 


10 


4.90 


3.01 


1: 0.62 


11 


5.07 


3.13 


1 : 0.62 



VARIATIONS OF MILK CONSTITUENTS 



167 



These results show a remarkable uniformity in the 
ratio of fat to casein throughout the lactation period. 
The ratio remains quite constant for seven or eight 
months and then increases slightly, remaining the 
same during the rest of the lactation period. 

It will be of practical interest in this connection to 
observe what the relation of fat and casein is during 
the season in the case of the mixed milk of many 
herds of cows, as obtained at New York cheese fac- 
tories 



RELATION OF FAT AND CASEIN IN CHEESE-FACTORY 
MILK DURING SEASON 



Month 



April 

May 

June 

July 

August . . . . 
September 
October. . . 



Per cent 
of fat 



3.43 
3.58 
3.64 
3.62 
3.84 
3.92 
4.23 



Per cent 
of casein 



2.29 
2.34 
2.47 
2.43 
2.39 
2.55 
2.81 



Parts of casein for 
one part of fat 



Fat : Casein 



0.67 
0.65 
0.68 
0.67 
0.62 
0.65 
0.66 



The same fairly uniform relation holds except m 
the case of the month of August, when the casein 
decreased relative to fat. It is interesting to notice 
how closely the relation of fat and casein in cheese- 
factory milk agrees with that of the Holstein-Friesian 
and Ayrshire types as given in the table on p. 165. 
The cheese-factory cows were grade Holsteins and 
Ayrshires to a considerable extent 

Influence of fresh pastures and of drouth upon 
the relation of fat and casein in milk. — Using the 
data already given, we have the following tabular 



1 68 SCIENCE AND PRACTICE OF CHEESE-MAKING 

statement in regard to the influence of turning cows 
from barn into pasture about the middle of May : 



First half of May. . , 
Second half of May 



Per cent 

of fat 

in milk 



3.46 
3.70 



Per cent 
of casein 
in milk 



2.25 
2.45 



Parts of casein for 
one part of fat 



Fat: Casein 

1: 0.65 
1: 0.66 



It is seen that under the conditions indicated, 
the fat and casein maintain a relation that is very 
uniform. 

Turning now to data obtained during a summer 
when extreme drouth prevailed during part of July 
and all of August, we have the following results : 



EFFECT OF DROUTH UPON RELATION OF FAT TO CASEIN 

IN MILK 



Month 



May 

June 

July 

August. . . . 
September 
October. . . 



Per cent 
of fat 



3.58 
3.59 
3.71 
4.04 
3.97 
4.20 



Per cent 
of casein 



2.40 
2.33 
2.20 
2.26 
2.47 
2.69 



Parts of casein for 
one part of fat 



Fat : Casein 

1: 0.67 
1: 0.65 
1: 0.59 
1:0.56 
1: 0.62 
1: 0.64 



These results show, for cheese-factory milks, an 
abnormal ratio of fat and casein in July which was 
still further from normal in August. In Septem- 
ber, when abundant rains came and when, in addi- 
tion, dairymen had fodder corn to supplement 
pastures with, the ratio became more nearly nor- 
mal and still more so in October. From the stand- 
point of practical application, these facts iadicate 



VARIATIONS OF MILK CONSTITUENTS 169 

the necessity for dairymen to guard against the 
effects of drouth by making provision for furnish- 
ing some form of succulent food then. At such 
times, there is an enormous loss due to shrinkage 
in yield of milk; and, in cheese-making, there is an 
abnormal loss of fat in whey, resulting in decreased 
yield of cheese for loo pounds of milk. 

THE RELATION OF FAT AND CASEIN IN 
CHEESE-FACTORY MILK 

We have seen that the relation of fat and casein 
is a variable one, the variations being less wide, of 
course, in the case of herd milk than in that of 
individual cows, and especially of single milkings 
of individuals. But, in the case of averages of 
several analyses of milk and in the case of milk 
of herds, especially when cows are of one general 
type in respect to breed, a certain degree of uniform- 
ity exists in the relation of fat to casein. In New 
York a careful study was made of the milk of each 
of 50 different herds of cheese-factory cows during 
one season (May to October), and, as one of the 
results, a general relation was noticed between the 
fat and casein. In general, it was found that when 
the fat in milk increases i.o per cent, there is an 
average increase of casein amounting to 0.4 per 
cent. This was found to hold quite satisfactorily 
when applied in case of ordinary herd milk varying 
in fat content from 3 to 4.5 per cent and, in many 
cases, outside of these limits. In milk containing 
less than 3 per cent of fat, the casein content is 
usually higher in relation to fat than in milk with 
more than 3 per cent of fat ; while, Jn the case of 



170 SCIENCE AND PRACTICE OF CHEESE-MAKING 

milk containing more than 4.5 per cent of fat, the ratio 
of casein to fat is frequently less than in milk con- 
taining less than 4.5 per cent of fat. Starting with 
milk containing an average of 3 per cent of fat and 
a casein content of 2.1 per cent, milk with 4 per cent 
of fat was found to contain about 2.5 per cent of 
casein on an average. 

RULE FOR CALCULATING AMOUNT OF 
CASEIN IN MILK 

On the basis of the observed general relations stated 
above, the following formula was worked out for cal- 
culating the percentage of casein in milk when the per 
cent of fat is known : 

(F — 3) Xo.4+2.i=per cent of casein. 

F equals the number representing the per cent of fat 
in milk. Expressed as a rule, we have the following: 
From the number representing the per cent of fat 
in milk subtract 3 ; multiply the result by 0.4 and 
then add 2.1. The formula is apt to give results 
not quite up to the actual in case of milk produced 
Bfter the eighth or ninth month of lactation period, 
when the casein is usually a little greater in rela- 
tion to fat than during the previous stage of the 
lactation period. Applied separately to the milk 
of 50 herds of cows during the factory season, the 
average results for the season are summarized as 
follows : ( I ) In 4 cases, the results found by chemi- 
cal determination were identical with those given 
by calculation ; (2) in ;^6 cases, the results by cal- 
culation were within o.i per cent of those obtained 
by the chemical method; (3) in 8 cases the chemi- 
cal method gave o.i to 0.2 per cent less than the 



VARIATIONS OF MILK CONSTITUENTS I7I 

calculated amount; (4) in 2 cases the calculated per 
cent exceeded that found by the chemical method to 
the extent of 0.23 and 0.25 per cent. It is thus seen 
that, taking the entire season's average, 80 per cent 
of the results by the method of calculation differed 
from those obtained with the chemical method by 
less than o.i per cent. The results given below 
represent the application of the formula in case of herd 
milk: 



Per cent of fat Per cent of casein in milk, as found by 

in milk (1) (2) 

Chemical method Calculation 

3.25 2.38 2.20 

3.31 2.19 2.22 

3.42 2.27 2.27 

3.52 2.30 2.30 

3.55 2.34 2.32 

3.55 2.18 2.32 

3.63 2.45 2.35 

3.63 2.33 2.35 

3.71 2.29 2.38 

3.71 2.48 2.38 

3.71 2.35 2.38 

3.84 2.44 2.44 

3.84 2.37 2.44 

3.92 - 2.42 2.47 

4.00 2.53 2.50 

4.14 2.50 2.56 

425 2.51 2.60 

4.31 2.37 2.62 



For ordinary purposes, where the strictest accu- 
racy is not required, the rule can be used with quite 
satisfactory results, when applied to herd milks 
within the limits specified, and most of our cheese- 
factory milks come within these limits. Of course, 
it is readily recognized that, when very accurate 
results are necessary, only a direct determination 
of casein by an accurate method can suffice for the 
purpose ; and, by an accurate method, is meant one 
which can be relied upon to give results within one- 
tenth of one per cent of the truth. 



iy2 SCIENCE AND PRACTICE OF CHEESE-MAKING 

AMOUNT OF FAT AND CASEIN IN ORDI- 
NARY FACTORY MILK 

In the case of ordinary cheese-factory milk, we may 
expect to find the fat and casein run somewhat as 
follows : 



Per cent of fat 


Per cent of casein 


in milk 


in milk 


3.00 


2.10 


3.25 


2.20 


3.50 


2.30 


3.75 


2.40 


4.00 


2.50 


4.25 


2.60 


4.50 


2.70 


5.00 


2.90 



Ratio of 


Fat 


Casein 




0.70 




0.68 




0.66 




0.64 




0.62 




0.61 




0.60 




0.59 



RELATION OF CASEIN AND ALBUMIN IN 

MILK 

It IS a matter of practical interest in connection 
with cheese-making to know whether, in milk with 
a high percentage of casein, there is also a propor- 
tionally high percentage of albumin. The higher 
the casein, relative to albumin, the greater is the 
proportion of cheese-producing constituents. We 
will study this question in relation to (i) breed and 
(2) stage of lactation. It should be- stated that 
albumin, as here used, includes all the proteins of the 
milk other than casein. 

In studying the results, it is noticeable that, in 
general, in the case of milk containing a low per- 
centage of fat (p. 165), the albumin forms a larger 
proportion of the proteins than in case of milk con- 
taining a high percentage of fat, when we compare 
the milk of different breeds of cows under corre- 
sponding conditions. Also, in milks low in fat, the 
casein forms a smaller proportion of the proteins 



VARIATIONS OF MILK CONSTITUENTS 



173 



INFLUENCE OF BREED UPON THE RELATION OF CASEIN 

AND ALBUMIN 



Name of breed 



Per cent 

of 

proteins 

(casein 

and 

albumin) 



Per cent 

of 

casein 



Per cent 

of 
albumin 



Parts of casein 
for one part 
of albumin 



Per cent 
of total 
proteins 

in form 
of 

casein 



Holstein-Friesian. . . . 

Ayrshire 

American Holdemess 

Shorthorn 

Devon 

Guernsey 

Jersey 



2.84 


2.20 


0.64 


Album 


3.07 


2.46 


0.61 




3.32 


2.63 


0.69 




3.43 


2.79 


0.64 




3.93 


3.10 


0.83 




3.56 


2.91 


0.65 




3.68 


3.03 


0.65 





3.4 
4.0 
3.8 
4.5 
3.7 
4.5 
4.7 



77.5 
80.1 
79.2 
81.3 
78.9 
81.7 
82.3 



than in case of milks higher in fat. Thus, in the 
milk of Holstein-Friesian cows, we have the least 
amount of fat (3.26 per cent), and the casein forms 
a smaller part (77.5 per cent), and the albumin a 
larger part (22.5 per cent), of the proteins than in 
case of any other breed under discussion. In the 
case of Guernsey and Jersey milk, in which the fat 
content is highest, the proportion of casein to pro- 
teins is greatest (about 82 per cent), while it is least 
for albumin (about 18 per cent). In its practical 
application, these results mean that, in the case of 
Jersey and Guernsey milk, a larger proportion of the 
proteins is utilized in cheese-making and a smaller 
proportion is lost in whey. 

The relation of casein and albumin, as shown by 
the following data, is remarkably uniform during 
the first eight or nine months of lactation, varying 
between 4.1 and 4.2 parts of casein for one of 
albumin ; or, stated in another way, the percentage 
of total proteins in the form of casein varied from 
80.3 to 80.9 and, in the form of albumin, from 19. 1 



1/4 SCIENCE AND PRACTICE OF CHEESE-MAKING 

INFLUENCE OF STAGE OF LACTATION UPON THE RELA- 
TION OF CASEIN AND ALBUMIN 



Month 

of 

lactation 


Per cent 
of Proteins 
(casein and 

albumin) 


Per cent 

of 

casein 


Per cent 

of 
albumin 


Parts of casein 

for one part 

of albumin 

Albumin: Casein 


Per cent of 

total 

proteins in 

form of 

casein 


1 


3.16 
2.99 
3.04 
3.13 
3.25 
3.33 
3.40 
3.47 
3.57 
3.79 
4 04 


2.54 
2.42 
2.46 
2.52 
2.61 
2.68 
2.74 
2.80 
2.90 
3.01 
3.13 


0.62 
0.57 
0.58 
0.61 
0.64 
0.65 
0.66 
0.67 
0.67 
0.78 
0.91 




4.1 
4.2 
4.2 
4.1 
4.1 
4.1 
4.2 
4.2 
4.3 
3.9 
3 4 


80 4 


2 


80 9 


3 


80.9 


4 


80 5 


5 


80 3 


6 


80 5 


7 


80.6 


8 

9 


80.7 
81 2 


10 


79 4 


11 


77.5 











to 19.7. After the ninth month, the albumin in- 
creases relative to casein, the increase being very- 
marked in the two closing months of the lactation 
periods studied. 

In the case of the mixed milk of numerous herds 
of cheese-factory cows, we have the following re- 
sults : 



Month 

April 

May 

June 

July 

August 

September. . 
October. . . . 



Per cent 






of protein 


Per cent 


Per cent 


(casein and 


of 


of 


albumin) 


casein 


albumin 



2.81 
3.02 
3.24 
3.07 
3.02 
3.20 
3.55 



Parts of casein 
for one part 
of albumin 







Album 


2.29 


0.52 




2.34 


0.68 




2.47 


0.77 




2.43 


0.64 




2.39 


0.63 




2.55 


0.65 




2.81 


0.74 





4.4 
3.4 
3.2 
3.8 
3.8 
3.9 
3.8 



Per cent 

of total 

proteins in 

form of 

casein 



81. S 
77.5 

76.2 
79.2 
79.1 
79.7 

79.2 



The proportion of casein in relation to albumin 
decreases until July, when a marked increase oc- 



VARIATIONS OF MILK CONSTITUENTS 



175 



curs; and then the ratio remains uniform durmg 
the rest of the season, which extends approximately 
through the seventh or eighth month of lactation. 

The general statement has been prominently cur- 
rent in literature to the effect that casein and al- 
bumin are present in cow's milk in very constant 
relative proportions, the amount of casein being five 
times that of albumin. In the case of herd milks, 
we have found casein varying all the way from 2.6 
to 5.6 parts for one part of albumin. In single milk- 
ings of individual cows, the variations are considerably 
wider. 

The following figures represent the average 
monthly composition of milk as obtained at cheese- 
factories in New York state. These data repre- 
sent the work of several seasons and are taken 
from the records of the New York experiment 
station : 



Month 



Solids 



Fat 



Casein 



Albumin 



Sugar, 
ash, etc. 



April 

May 

June 

July 

August. . . . 
September 
October. . . 

Average . . . 



11.98 
12.43 
12.64 
12.52 
12.65 
12.86 
13.50 



12.67 



3.43 
3.58 
3.64 
3.62 
3.84 
3.98 
4.23 



3.75 



2.29 


0.52 


2.34 


C.68 


2.47 


0.77 


2.43 


0.64 


2.39 


0.63 


2.55 


0.65 


2.81 


0.74 


2.46 


0.68 



5.74 
5.83 
5.76 
5.83 
5.79 
5.68 
5.72 



5.78 



The following figures show the extreme variations 
in composition of cheese-factory milk during the 
season : 



176 SCIENCE AND PRACTICE OF CHEESE-MAKING 





Lowest 
per cent 


Highest 
per cent 


Solids 


11.47 
3.04 
1.93 
0.47 
5.32 


13.91 


Fat 


4.60 


Casein 


3.00 




0.88 




6.37 







For a more general and, in some .respects, more com- 
plete discussion of the chemistry of milk, the reader 
is referred to "Modern Methods of Testing Milk and 
Milk Products," published by Orange Judd Company. 



CHAPTER XVI 

Functions of MOk Constituents in 
Cheese-Making 

Having- considered the properties and amounts of 
different constituents in milk in connection with 
cheese-making, it is a matter of interest to notice what 
particular part each performs in the process or what 
particular contribution of value each makes to the 
fini-shed product. It will be found that each con- 
stituent has a value peculiar to itself in relation to 
cheese and the process of cheese-making. 

MILK-FAT 

Milk- fat is the object of solicitous care on the 
part of the intelligent cheese-maker, and its pecu- 
liarities have much to do with certain details of 
the cheese-making process. Its part in the actual 
process of cheese-making is, however, a passive 
rather than an active one, since the details of the 
operations are governed, to a considerable extent, 
by the aim of retaining as much milk-fat as pos- 
sible in the cheese and losing the smallest possible 
amount in whey. The reasons for keeping milk-fat 
in cheese are twofold, (i) on account of its influence 
on the yield of cheese and (2) on account of its effect 
upon the quality of the cheese. 

So far as we know at present, milk-fat contributes 
little or nothing to the flavor of normal cheddar 

X77 



1/8 SCIENCE AND PRACTICE OF CHEESE-MAKING 

cheese; but its chief functions, in relation to quaHty 
of cheese, appear to be to give (i) a characteristi:- 
meHowness of body, (2) smoothness of feehng, (3) 
richness and dehcacy of taste and (4), in general, 
palatability. No other constituent can take its 
place in performing any of these offices. Of course, 
the high value of milk-fat as a food should not be 
lost sight of, but this fact does not necessarily enter 
into the question of quality of cheese as affected 
by the presence of fat. The peculiar and exclusive 
function of milk-fat in giving to cheese certain 
desirable qualities can be well appreciated by com- 
paring different kinds of cheese, equally well made 
and differing only in the percentage of fat contained 
in them, as, for example, cheese made from normal 
milk containing added cream, cheese made from 
normal Jersey milk, cheese made from Holstein- 
Friesian milk, and cheese made from milk skimmed 
in varying degrees, down to separator skim-milk 
cheese. 

The relation of fat to yield of cheese will be con- 
sidered in detail in the next chapter. 

MILK-CASEIN 

Casein Is the constituent of milk which, on ac- 
count of its peculiar action toward rennet-extract 
solutions, makes possible the manufacture of ched- 
dar and many other kinds of cheese. In the pro- 
cess of cheese-making, it performs two specific 
functions : ( i ) In its solidification, its first work is 
to imprison the fat-globules in the curd and then 
continue to hold them as firmly as possible through- 
out the manipulations of cheese-making. (2) Its 



FUNCTIONS OF MILK CONSTITUENTS I79 

second function is to retain whey in the curd in 
desired amounts, while, at the same time, permit- 
ting superfluous whey to escape from the mass of 
curd. The power of casein to hold moisture is 
somewhat like that of a sponge. Special experi- 
ments at the New York experiment station have 
shown that one pound of dry casein can easily 
absorb and hold about one pound and a quarter of 
water. P'at has, of course, comparatively little 
water-holding power, so that this function falls 
almost entirely on casein. It is obvious that this 
special work can be done by no other constituent 
of milk, and thus casein is recognized as the water- 
holder in cheese. 

In the finished product, casein, or rather, the 
compound formed from it, performs two important 
and peculiar functions. ( i ) It gives to the cheese 
firmness and solidity of body under a wide range 
of temperature, conditions which are requisite for 
its keeping and convenient handling. The casein- 
derived product in reality constitutes the firm 
framework or skeleton which gives permanence to 
the form of the cheese. (2) It furnishes the protein 
material in which, it is believed, take place those 
changes that result in characteristic cheese flavors, 
while, at the same time, it is converted into soluble, 
nutritive compounds, which add largely to the value 
of the cheese as food. The peculiar properties of 
casein when made into cheese are such that its 
presence in excess in relation to fat or moisture 
causes serious deterioration in some of the proper- 
ties of the cheese. For instance, when an excess of 
casein is used, as in the case of skim-milk cheese, 



l80 SCIENCE AND PRACTICE OF CHEESE-MAKING 

the desirable firmness of body becomes objectionable 
hardness, unless the conditions of manufacture are 
so modified as to Hold more whey in cheese, in which 
case objectionable properties of another kind are apt 
to result. 

WATER 

As we shall see later, when we come to stud}- 
the composition of cheese, water is one of the most 
prominent constituents in amount. We have al- 
ready indicated why the amount of water in normal 
milk has little interest in connection with cheese- 
making, but its presence in cheese is of great 
interest and the problem of its control in the cheese- 
making process is one of the highest importance. 
Water performs two chief functions in cheese : 
(i) It influences the character of the body in 
cheese, imparting to it smoothness and a certain 
degree of mellowness, and (2) it furnishes suitable 
conditions for the work of those agents which 
change insoluble cheese proteins into soluble forms 

(p. 353)- 

In performing the first of these functions, water, 
therefore, supplements the work of fat but cannot 
take its place in imparting richness and delicacy of 
taste. In the manufacture of skim-milk cheese, an 
effort is usually made to imitate the mellowness of 
body characteristic of a cheese made from normal milk, 
which is due to fat, by holding in the cheese a large 
amount of moisture. In illustration of this fact, 
we have examined cheese containing over 50 per 
cent of water, the cheese having been made from 
separator skim-milk. Unless this large amount of 



FUNCTIONS OF MILK CONSTITUENTS l8l 

moisture is retained, the cheese is hard, tough and 
unj^felatable. Even in cheese made from normal 
milk, the body becomes dry and mealy or crumbly, 
if the amount of moisture falls much below 30 per 
cent. The higher the fat content of the cheese, the 
lower can be the amount of water without impair- 
ing the body of the cheese. The temptation is often 
strong in making cheese to incorporate 5 per cent 
or more of moisture beyond the usual amount, be- 
cause water is the only cheese constituent that can 
be had free of cost. The aim of cheese-makers 
should be so to control conditions of manufacture as 
to retain in cheese only the proper amount of moisture 

(p. 382). 

We have already stated that another function of 
water in cheese is to furnish conditions suitable for 
the work of those agents which convert insoluble 
cheese proteins into soluble forms. If the amount 
of water is below a certain limit, 25 to 2y per cent, 
these changes do not take place and the cheese fails 
to become edible. 

Some erroneously think that water in cheese is 
of a peculiar kind and possesses a special value as 
such, — that it is really different from water as we 
find it elsewhere. One writer goes so far as to 
speak of the water in cheese as ''natural water," 
''natural moisture," as if it possessed some unusual 
virtue because it had gone through a cow and 
formed a part of milk before going into cheese as 
"natural" water. Such a belief is quite without 
foundation, because the water in cheese can be 
easily separated from the cheese and examined and 
is known to possess the usual composition of water 



l82 SCIENCE AND PRACTICE OF CHEESE-MAKING 

wherever we find it. It is true, of course, that the 
presence of water in cheese is masked by the casein 
and fat and one of the aims of the cheese-maker is 
to conceal it thus as completely as possible ; but this 
fact has no bearing on the composition or character 
of the water itself. 

MILK-SUGAR 

The only function milk-sugar appears to per- 
form in the process of cheese-making is to fur- 
nish material for making lactic acid. Lactic acid 
does not remain in milk as free or uncombined 
acid, but, as fast as formed, it acts upon some of the 
salts of the milk, especially insoluble calcium phos- 
phate, combining with a portion of the calcium and 
forming calcium lactate and soluble or acid calcium 
phosphate, an acid salt. There are probably other 
salts in milk acted upon, about the details of which 
we have not yet obtained complete knowledge. These 
soluble calcium salts (calcium lactate, and acid cal- 
cium phosphate, including probably also acid calcium 
citrate) resulting from the action of acid furnished 
by the fermentation of milk-sugar, perform several 
functions in the cheese-making process. 

(i) These soluble calcium salts favor the rapid- 
ity and completeness of the action of rennet-extract 
in coagulating milk; in fact, their presence in cer- 
tain amounts is essential to the action of the ren- 
net-enzym. Now, while the immediate object of 
ripening milk in cheese-making is to convert milk- 
sugar into lactic acid, the real purpose is the forma- 
tion of soluble calcium salts to hasten rennet 
coagulation. 



FUNCTIONS OF MILK CONSTITUENTS 1 83 

(2) The soluble calcium salts probably perform 
some work in assisting in the contraction of the 
curd. ■ After the curd is formed in the cheese-vat, 
the milk-sugar remains in the coagulated mass at 
hrst, but gradually passes out in solution as the 
whey exudes from the pieces of curd. The amount 
of sugar remaining in the curd is much reduced, 
but the formation of lactic acid continues, thus in- 
creasing the amount of calcium lactate, acid calcium 
phosphate, acid calcium citrate, etc. Cheese-makers 
speak of acid in curd frequently when they really mean 
whey or, more strictly, milk-sugar contained in whey 
within the pieces of curd and ready to form lactic acid 
sooner or later. 

(3) The formation of soluble calcium salts is 
probably also more or less intimately connected 
with the changes in the curd during the cheddaring 
process, when the grain or texture rapidly changes, 
finally resembling the fiber of the cooked meat on 
a chicken's breast and when the curd develops the 
characteristic plastic properties ^^exhibited by form- 
ing long, silky strings, when brought into contact 
with a hot iron. This change appears to depend upon 
the conversion of paracasein into a substance soluble 
in brine solution (p. 147). 

The conversion of milk-sugar into lactic acid, 
with consequent formation of increasing quantities 
of soluble calcium salts, continues quite rapidly 
throughout the cheese-making process and also in 
the press and still later in the cheese. Under ordi- 
nary conditions, the last trace of milk-sugar disap- 
pears in about two weeks after the cheese is made. 
But, throughout the process of cheese-making, when 



184 SCIENCE AND PRACTICE OF CHEESE-MAKING 

the conditions are normal, there is never enough sugar 
converted into lactic acid to combine with all the avail- 
able calcium in cheese and form free lactic acid ; and 
there is never left in the cheese, under normal con- 
ditions, enough milk-sugar to form free acid. There- 
fore, in normal cheddar cheese, we never have free 
lactic acid. 

When a large amount of whey is left in cheese, 
that means a corresponding amount of milk-sugar, 
a correspondingly large amount of acid, with forma- 
tion of increased amounts of calcium salts, resulting 
in the production of what is known as "acid" or ''sour" 
cheese. 

(4) Another well-recognized function of milk- 
sugar, as a result of the formation of lactic acid and 
acid salts in milk, is the prevention of the growth 
of other micro-organisms which are often present 
in milk and give rise to forms of fermentation that 
interfere seriously with the production of good 
cheese, such as the micro-organisms that produce 
gases, ill-smelling compounds, etc. It is known that, 
if the acid salts and milk-sugar in cheese-curd are 
removed, as is done in the case of the ''soaked- 
curd" process (p. 57), the resulting cheese undergoes 
abnormal changes in ripening, forming products that 
are putrefactive in character and which seriously im- 
pair or destroy the value of the cheese as food. 

SALTS OF MILK 

The salts of milk appear, as already explained in 
connection with the functions of milk-sugar, to 
depend largely for the active part which they take 
in cheese-making upon the presence of lactic acid, 



FUNCTIONS OF MILK CONSTITUENTS 185 

by which insoluble calcium salts are converted into 
soluble forms, especially soluble calcium phosphate. 
When we determine the acidity of whey at various 
stages of the operations of cheese-making, we are 
really measuring directly the formation of acid com- 
pounds, which furnish, of course, a measure of the 
amount of lactic acid that has been formed. 

It has been noticed that, when in the making of 
cheese a higher degree of acidity is produced, while 
the curd is still in the whey, that the amount of ash 
in the cheese is less than when so much acid is not 
formed. This is in accordance with what one would 
expect, since the more rapidly the insoluble calcium 
salts are dissolved while the curd is in the cheese-vat, 
the larger is the amount of soluble salts going into 
the whey. 



CHAPTER XVII 
Milk Constituents and Yield of Cheese 

The relation of the composition of milk to yield 
of cheese is a subject of the highest practical in- 
terest and importance to cheese-makers. Compara- 
tively little was known about it previous to 1892, 
because attention had been completely absorbed by 
the merely mechanical methods of cheese-making. 
We were completely in the dark in regard to such 
fundamental facts as the relation of fat and casein 
in milk to yield of cheese, the character and extent 
of losses of milk constituents in cheese-making, 
their causes and remedies, and, in general, the de- 
tailed relations existing between cheese and the 
material from which it is made. So profound was 
the ignorance regarding milk constituents and their 
relation to yield of cheese that it was very gener- 
ally believed that the same amount of cheese was 
made from 100 pounds of milk in the case of the 
milks of different herds. We now have on hand an 
immense mass of data, the accumulated results of 
the investigation work of our American experiment 
stations, and these data enable us to reach very 
definite, positive and final conclusions. 

The amount of fresh or green cheese produced by 
100 pounds of milk depends upon three factors: 

( 1 ) The percentage of fat and of casein in milk. 

(2) The percentage of fat and of casein lost in 
cheese-making. 



186 



MILK AND YIELD OF CHEESE 187 

(3) The amount of whey retained in cheese. 

THE RELATION OF FAT AND OF CASEIN 
TO YIELD OF CHEESE 

Those constituents of the milk that are insoluble 
and are present in suspension as solids or in emul- 
sion, those that can be, for the most part, mechan- 
ically held by the coagulated casein, furnish the 
solid materials for cheese. They are : ( i ) Milk- 
fat; (2) milk-casein; and (3) insoluble phosphates. 
The fat and casein constitute so large a proportion 
of these cheese-producing solids of milk that we 
should not be far from the truth in saying that 
only these two constituents of normal milk are 
prominent in determining the yield of cheese. These 
two constituents of milk form over 90 per cent of 
the solid portion of cheese (cheese-solids) ; the only 
other solids in cheese are comparatively small in 
amount, consisting essentially ( i ) of the calcium 
salts of phosphoric, lactic and citric acids; (2) of the 
salt added in cheese-making; (3) of a small amount 
of milk-albumin; and (4) of some milk-sugar, which 
mostly disappears in a few days. 

The yield of cheese from milk varies as the 
amount of fat and casein in milk vary, provided the 
conditions of cheese-making are the same, includ- 
ing under these conditions the quality of the milk 
with reference to cleanliness (bacterial content), (p. 
4). As a rule, when the percentage of fat in milk 
increases, the percentage of casein also increases (p. 
169) and the yield of cheese increases in proportion 
to the increase of fat and casein. At this point, the 



l88 SCIENCE AND PRACTICE OF CHEESE-MAKING 

questions naturally arise : How much does milk-fat 
contribute to cheese yield? How much does milk- 
casein contribute to cheese yield? This at once 
brings us to a consideration of the losses of these 
constituents in the process of cheese-making. 

THE LOSSES OF MILK CONSTITUENTS IN 
CHEESE-MAKING 

In transferring fat and casein from milk into 
cheese through the operations of cheese-making, 
certain amounts of these constituents are unavoid- 
ably lost in the escaping whey and do not, conse- 
quently, contribute to the yield of cheese. It is 
obvious, therefore, that the cheese yield from a 
given amount of milk is dependent, to some extent, 
upon the degree of completeness with which the 
fat and casein of milk are worked into cheese ; that 
is, upon the degree of success experienced in re- 
ducing these losses to a minimum. It is very im- 
portant, then, that in studying the relation of milk 
constituents to yield of cheese, we learn something 
of the extent to which such losses are found in actual 
experience, the conditions responsible for these losses, 
and the means by which they can be made as small 
as possible. 

The losses of milk-fat in cheese-making. — Less 
than 20 years ago cheese-makers almost universally 
believed that all fat in milk above 3.5 or 4.0 per 
cent must go into whey and not into cheese. Breed- 
ers of cows giving milk low in fat content openly 
declared, and without contradiction, that only cows 
of this type could be suitable for profitable cheese- 
making, because it was impossible to transfer the 
extra milk-fat into cheese when milk contained over 



MILK AND YIELD OF CHEESE 189 

3.5 per cent. This question has been studied ex- 
haustively in the New York experiment station 
under a great variety of conditions, including extended 
investigations in case of actual operations in many 
different cheese-factories. The following institu- 
tions have contributed additional, though less exten- 
sive, data, which fully confirm the results obtained 
in New York : The experiment stations of Wiscon- 
sin, Minnesota, Iowa, Vermont, Utah and the 
Ontario Agricultural college. Probably much un- 
published work has been done elsewhere. 

Taking the results of extended study under 
cheese-factory conditions, we have found that the 
amount of fat lost for lOO pounds of milk varies 
from 0.20 to 0.50 pound (equivalent to 0.22 to 0.55 
per cent of fat in whey), the average being 0.33 
pound (equivalent to 0.36 per cent of fat in whey). 
This amounts to about 9 per cent of the fat in the 
milk. In one factory which was under observation 
for an entire season, the loss of fat for 100 pounds 
of milk varied from 0.20 to 0.36, and averaged 0.25, 
pound (equivalent to 0.22, 0.40 and 0.27 per cent 
of fat in whey). This average is equivalent to 7 
per cent of the fat in the milk. In another factory, 
which was under observation at the same time, 
the amount of fat lost varied from 0.26 to 0.50, 
and averaged 0.37, pound (equivalent to 0.29, 0.55 
and 0.42 per cent of fat in whey). The average 
loss in this case is nearly 10 per cent of the fat in 
the milk. In some cases, losses of fat under 0.20 
pound have been reported, but such experience is 
not common in most cheese-factories. In general, 
it may be said that really efficient work is not 



190 SCIENCE AND PRACTICE OF CHEESE-MAKING 

being clone by a cheese-maker when the percentage 
of fat in whey exceeds 0.30, if the milk furnished 
is in good condition in respect to cleanliness. An 
average loss of 0.25 pound (4 ounces) of fat for 100 
pounds of milk indicates excellent work under factory 
conditions ; this means that about 93 per cent of the 
fat in milk is recovered in cheese and not over 7 per 
cent lost in whey. 

The data embodied in the following table include 
the results of several seasons' work in cheese-fac- 
tories : 



AMOUNT OF FAT IN WHEY AT CHEESE-FACTORIES DUR- 
ING SEASON 



Month 



Average 

per cent of 
fat in milk 



Pounds of fat lost in whey from 
100 pounds of milk 



April 

May 

June 

July 

August . . . . 
September 
October. . . 



3.43 
3.58 
3.64 
3.62 
3.84 
3.98 
4.23 



Lowest 
0.29 
0.20 
0.20 
0.21 
0.22 
0.22 
0.26 



Highest 
0.42 
0.50 
0.36 
0.45 
0.40 
0.46 
0.44 



Average 
0.36 
0.35 
0.28 
0.32 
0.34 
0.37 
0.33 



The tabulated results on the next page show the 
relative amounts of fat lost in normal milks containing 
different percentages of fat. These results are in 
harmony with those of other investigators and the 
facts all go to show that the loss of fat in cheese- 
making is quite independent of the amount of fat in 
milk. The variations that occur in loss of fat are 
due either to the defective condition of the milk with 
reference to bacterial content, or to some special fault 
in the details of methods employed in cheese-making, 
or to both causes. 



MILK AND YIELD OF CHEESE 



191 



Even when cream is added to normal milk to an 
extent sufficient to raise the fat content to 7 or 8 
per cent, the increased loss of fat, though consider- 
able, is not necessarily greater in proportion to the 
increase of fat in milk. 



AMOUNT OF FAT LOST IN CHEESE-MAKING IN CASE OF 
NORMAL MILKS 















Percent- 


Percent- 




Number 


Per cent 








age of fat 


age of fat 


Group 


of ex- 


of fat 


Pounds 


of fat lost 


in whey 


in milk 


in milk 




peri- 


in milk 


for lOu pounds 


of milk 


lost in 


retained 




ments 










whey 


in cheese 








Lowest 


Highest 


Average 






I 


22 


3.0-3.5 


0.21 


0.39 


0.32 


9.55 


90.45 


II 


112 


3.5-4.0 


0.21 


0.50 


0.33 


8.33 


9LC7 


III 


78 


4.0-4.5 


0.20 


0.46 


0.32 


7.70 


92.50 


IV 


16 


4.5-5.0 


0.17 


0.49 


0.28 


5.90 


94.10 


V 


7 


5.0-5.25 


0.27 


0.35 


0.31 


6.00 


94.00 



Why it is impossible to prevent loss of fat in 
cheese-making. — Attention has already been called (p. 
191) to the fact that fat is present in milk in the 
form of very small globules, one cubic centimeter 
of ordinary milk containing between one and two 
billion globules. When the rennet-extract causes 
the casein throughout the mass of milk to solidify 
or coagulate, the fat-globules are retained or im- 
prisoned in the solidified mass just where they 
are at the instant of coagulation. When the curd- 
knife passes through the solid mass, immense num- 
bers of the fat-globules are exposed on every cut 
surface and billions of these are disengaged from 
the free surfaces of the small pieces of curd during 
its manipulation. The fat-globules, thus detached 



192 SCIENCE AND PRACTICE OF CHEESE-MAKING 

from the hold of the curd, float free in the whey and 
are consequently lost to the cheese. 

Conditions favoring loss of fat in cheese-making. 
—Among the numerous conditions contributing to 
an increased loss of fat in cheese-making are the fol- 
lowing : 

(i) Any condition which interferes with com- 
plete coagulation of casein by rennet-extract, such 
as dilution with water, presence of preservatives, 
as salt, formalin, etc., necessarily causes extra loss of 
fat. 

(2) There may occur cases of abnormal compo- 
sition of milk, in which the casein is abnormally 
low in relation to fat. Attention has already (p. 
164) been called to this condition as likely to occur 
in times of drouth. Cheese-makers do not realize 
the abnormal nature of the milk and so do not ob- 
serve the precautions necessary in handling milk 
that is abnormally high in fat in relation to casein. 
But another condition usually prevails at such times, 
which makes the losses of fat unavoidable, and that is 
the presence of bacterial ferments, resulting from the 
accompanying effects of drouth such as contaminated 
water supply. 

(3) Failure to keep the fat well distributed 
through the milk before and after adding rennet 
results in some accumulation of fat at the surface 
of the milk, most of which goes into the whey. 

(4) In case of milk containing particles of dried 
cream or churned fat-granules, there is usually in- 
creased loss of fat, unless the particles are completely 
worked back into the form of emulsion by sufficient, 
but not rapid, warming and careful stirring. 



MILK AND YIELD OF CHEESE I93 

(5) When milk is run throug-h a separator and 
the cream and skim-milk then remixed, increased 
loss of fat occurs when such milk is made into 
cheese. 

(6) Jarring- or stirring milk after rennet coagu- 
lation has commenced and before it is completed may 
cause serious loss of fat. 

(7) When curd is cut in too soft a condition, the 
loss of fat is greater. 

(8) Added losses of fat in whey are caused by 
dull knives or by violent, careless and rapid motions 
of knife in cutting curd. 

(9) Extra losses of fat occur when the curd in the 
soft stage is roughly or carelessly handled. 

(10) Another cause of increased loss of fat in 
whey is heating the curd too rapidly or to too high a 
temperature. 

(11) If the curd is not well firmed at the time 
the whey is removed, vigorous hand stirring causes 
large loss of fat. 

(12) Excessive piling of curd, previous to ched- 
daring, causes unnecessary loss of fat. 

(13) If the curd is salted at a temperature above 
90° F., fat is apt to exude along with the whey and 
be lost. 

(14) If curd is put in press too warm, the amount 
of fat lost in pressing increases on account of the 
greater softness of the warm curd. 

(15) Too rapid application of pressure in the 
cheese-press increases loss of fat. 

(16) Fermentations producing large amounts of 
gas and resulting in "floating" curds, also curd- 
dissolving fermentations, are attended with extra 



194 SCIENCE AND PRACTICE OF CHEESE-MAKING 

losses of fat. The conditions of cheese-making have 
to be varied under such circumstances so as to make 
the best of a bad matter and obtain as good a product 
as possible in respect to texture, body and flavor. 
Such variations from the usual conditions of cheese- 
making cause extra losses of fat (p. 124). 

(17) The making of cheese from milk containing 
too much acid results in unusual losses of fat, if the 
conditions are varied so as to obtain the best product 
possible from such milk (p. 122). 

(18) Milling at too high a temperature, or too 
rapidly, or with dull knives, or feeding to mill too 
fast, or allowing the curd to become matted after 
milling, — any of these conditions increases loss of 
fat. 

The losses of casein in cheese-making. — The 
larger portion of the casein lost in cheese-making 
appears to be in the form of fine particles of the 
coagulated casein (paracasein), which pass through 
the strainer when the whey is removed from the 
curd. These fine particles can readily be seen by 
letting a pail of freshly drawn whey stand until the 
curd particles settle. If the whey is then carefully 
poured from the pail, a noticeable quantity of finely 
divided curd can be seen at the bottom of the pail. 
This loss does not appear to be entirely avoidable. 
but is needlessly made greater (i) by carelessness 
or violence in cutting curd and in subsequent han- 
dling when the curd is still soft; (2) by agitation 
while removing the whey from the curd; (3) by 
imperfect strainers ; and (4) by any condition that 
interferes with the complete coagulation of the 
milk-casein by rennet (p. 24). The amount of 



MILK AND YIELD OF CHEESE I95 

casein that thus passes into the whey averages about 
o.io pound for lOO pounds of milk. 

In some cases of badly contaminated milk, casein- 
dissolving- ferments may cause more or less loss of 
casein. 



FIG. 34 — COMPOSITION OF MILK, SHOWING PROPORTIONS OF 
WATER AND DIFFERENT SOLIDS. THE NUMBERS REP- 
RESENT POUNDS IN 100 POUNDS OF MILK 

COMPOSITION OF WHEY 

The composition of whey (Fig. 35) varies ac- 
cording, to ( I ) the composition of the milk from 
which it comes, and (2) the losses of milk constit- 
uents due to conditions attending the operations 
of cheese-making. It is obvious that the larger the 
percentage of sugar, albumin and soluble salts in 



196 SCIENCE AND PRACTICE OF CHEESE-MAKING 

milk, the larger will be their amount in whey. The 
matter of losses of fat and casein we have already 
treated. The amount of acid in whey varies 
greatly, depending largely on the time when the 
determination of acidity is made. When the whey 
is removed from the curd, the acidity (equivalent 




FIG. 35 — DISTRIBUTION OF MILK CONSTITUENTS IN 

CHEESE AND WHEY 

From 100 pounds of milk, we obtain '10.6 pounds of cheese and 89.4 pounds of 
whey. The cheese contains 3.9 pounds of water, 3.7 fat, 2.4 casein, O.i salts and 
albumin and 0.2 su!,'ar. The whey contains 83.1 pounds of water, 5.25 sugar and 
salts, 0.28 fat, 0.10 casein and 0.67 albumin. The lower part of the diagram shows 
amount and composition of cheese. The remainder is whey (water and whey- 
solids.) 

to lactic a>cid) varies from 0.16 to 0.18 per cent, and 
this amount increases to the end of the cheese- 
making process. The whey, when it first separates 
from the curd, shows less acidity than the milk 
from which it comes, because the whey does not 



MILK AND YIELD OF CHEESE 



197 



contain the milk-casein, which, as we have seen 
(p. 145), has the power of neutraHzing considerable 
alkali, and of acting in this way like an acid. The 
percentage of sugar in whey depends upon the time 
when the whey is tested, the sugar decreasing in 
amount as it is changed into lactic acid. 

In closing this discussion of the losses of milk 
constituents in cheese-making, we give below tab- 
ulated results of work showing the composition of 
whey as obtained at cheese-factories in New York 
through the work of the New York experiment 
station. 

COMPOSITION OF CHEESE^FACTORY WHEY 



Month 


Per cent 
of water 


Per cent 
of solids 


Per cent 
of fat 


Per cent 

of proteins 

(chiefly 

albumin) 


Per cent 
of sugar, 
salts, etc. 


April 

May 


93.17 
92.98 
92.99 
93.05 
93.08 
93.18 
93.04 


6.83 
7.02 
7.01 
6.95 
6.92 
6.82 
6.96 


0.40 0.73 
0.38 1 0.81 
0.31 0.88 


5.70 
5.83 


June 


5.82 


July 

August 

September 

October 


0.35 
0.38 
0.41 
0.38 


0.83 
0.80 
0.85 
0.98 


5.77 
5.74 
5.56 
5.60 


Average 


93.04 


6.96 


0.36 


0.84 5.76 



The following figures show the extreme variations 
in the constituents of whey during the period of 
investigation : 





Lowest 
per cent 


Highest 
per cent 


Solids 


6.43 
0.22 
0.65 
5.39 


7.52 


Fat 


0.55 


Proteins 

Sugar, salts, etc 


1.07 
6.43 



198 SCIENCE AND PRACTICE OF CHEESE-MAKING 

THE RELATION OF WATER TO YIELD OF 

CHEESE 

As we have seen, the amount of soHds in cheese 
is determined by the amount of fat and casein in 
milk when the conditions of manufacture are nor- 
mal. When we come to consider the amount of 
water held in cheese, we find that it bears no rela- 
tion whatever to the amount of water in milk, but 
that it is dependent upon the conditions present in 
the operations of cheese-making, such as the degree 
of fineness or coarseness in cutting curd, temper- 
ature used in heatmg curd, degree of acidity, 
amount of salt, etc. (p. 45). The amount of water 
in cheese can easily be made to vary 10 per cent. 
Fresh cheese contains an average of 37 per cent of 
water, but in actual factory work the variations may 
be very wide, especially where cheese is manufac- 
tured for export trade at one part of the season and 
for home trade at another. Therefore, when we are 
discussing yields of cheese from milk, and especially 
in the case of comparison of dififerent milks, it is 
absolutely necessary to know the percentage of 
water in the cheese. When we compare yields 
of cheese from different milks or under different con- 
ditions of manufacture, we should base our com- 
parison on the yield of cheese which contains a 
uniform percentage of moisture, if the results are 
to have any definite relation to the milk con- 
stituents. 

So important is it for us to appreciate the extent 
of variation of water in cheese, as made at cheese- 
factories, that we will present data obtained by the 
New York experiment station in 200 experiments 



MILK AND YIELD OF CHEESE 



199 



carried on at cheese-factories under the usual con- 
ditions. In the table below, we present the results 
in groups, based on the percentage of fat in milk; 
in each group we give (i) the extreme variations in 
yield of cheese; (2) the percentage of moisture 
in the cheese; and (3) the corresponding yield of 
cheese based on a content of 2^^ per cent of water. 



YIELD OF CHEESE AS AFFECTED BY MOISTURE 



Number 
of experi- 
ments 



Per cent 
of fat 
in milk 



Pounds of cheese 
made for 100 
pounds of milk 



Per cent 
of water 
in cheese 



Pounds of cheese 

(containing 37 per 

cent of water) 

made for 100 

pounds of milk 



22 
59 
51 
43 
25 



3.00-3.49 


{ 


3.50-3.74 


{ 


3.75-3.99 


1 


4.00-4.19 


1 


4.20-4.40 


( 



Lowest - 8.47 
Highest- 9.68 
Lowest - 9.25 
Highest-10.42 
Lowest - 9.60 
Highest- 11. 00 
Lowest -10.24 
Highest- 12.44 
Lowest -10.64 
Highest-13.17 



34.77 
39.09 
33.75 
40.47 
32.69 
40.17 
34.15 
42.90 
33.53 
43.89 



8.43 

9.46 

9.32 

10.60 

9.76 

10.76 

10.38 

10.93 

11.03 

12.03 



In studying these results, we see that In the case 
of each group the cheese yield varies widely, as 
shown in the third column of the table ; and also 
that the percentage of water varies widely, as 
shown in the fourth column. To illustrate, we 
will take the group representing milk containing 
4 to 4.19 per cent of fat. The factory yield . of 
cheese in this group varies from 10.24 to 12.44 
pounds, a difference of 2 pounds, while the water 
in 100 pounds of cheese varies from 34.15 to 42.90 
pounds. In the last column we see what the nor- 
mal variation should be in the yield of cheese 



20O SCIENCE AND PRACTICE OF CHEESE-MAKING 

having the same percentage (37) of water; it goes 
from 10.38 to 10.93, ^ variation of 0.55 pound, as 
against an actual variation of 2 pounds. This 
difference, 1.45 pounds, is wholly due to differ- 
ence of water in cheese. In the last group of 
the table, the factory yield of cheese varies 2.53 
pounds, while the normal variation would be only 
i.o pound. We see at the same time the amount 
of water in 100 pounds of cheese varies over 10 
pounds. 

These results might appear to indicate that 
cheese-makers have no control over the amount of 
water in cheese, but such a conclusion would not 
be justified, because it is well known that a skill- 
ful cheese-maker, under normal conditions, can 
control the amount of water in cheese within 3 
or 4 per cent, so that the normal range of varia- 
tion is usually between 35 and 38 per cent. The large 
amounts of water in the cases noted in the preceding 
table appeared there, not because the cheese-makers 
had no control of the process, but for the very opposite 
reason, that they did have such control and deliber- 
ately made the cheese to hold a high percentage of 
water 

THE COMPARATIVE VALUE OF DIFFER- 
ENT MILKS IN RELATION TO 
CHEESE-PRODUCING SOLIDS 

From what has preceded, it can be readily tni- 
derstood that we can divide the constituents of milk 
into two general classes, when considered with ref- 
erence to their relations to cheese. The casein, fat 



MILK AND YIELD OF CHEESE 201 

and insoluble salts constitute one group, furnishing 
most of the solid matter in cheese, and we can call 
these constituents cheese-producing solids. On an 
average, milk contains about 0.90 per cent of salts, 
of which about 0.25 pound goes into cheese for each 
TOO pounds of milk and 0.65 pound into whey, vary- 
ing, of course, with many conditions. The other 
constituents of the milk-solids, the sugar, the albu- 
min and the soluble salts, those constituents of the 
milk that exist in true solution, pass largely into 
the whey and are lost, except in so far as they are 
held by the water or whey in the cheese. Their 
amount in cheese will depend upon the amount of 
whey retained in the cheese. Those solid constitu- 
ents existing in solution in the whey we may prop- 
erly characterize as zvhey -solids. This division of milk 
constituents into cheese-producing solids and whey- 
solids is, of course, not strictly accurate, because 
small amounts of cheese-solids pass into whey and 
small amounts of whey-solids are retained in 
cheese. But, for the purpose of studying the gen- 
eral relations of milk-solids to cheese, the classifi- 
cation is close enough. The figures presented be- 
low are largely taken from work done at the New 
York experiment station, covering a period of four 
years and are largely derived from actual cheese- 
factory conditions. 

The cheese-producing solids were found to aver- 
age 6.50 pounds, varying in extreme cases from 
5.25 to 7.75 pounds for 100 pounds of milk, but the 
greater portion of factory milk comes within the 
narrower limits of 5.75 to 7.25 pounds. The whey- 
solids of milk varied from 5.75 to 6.75 pounds and 



202 SCIENCE AND PRACTICE OF CHEESE-MAKING 



averaged 6.25 pounds. Stated in another form, 49 
per cent of the milk-soHds goes into whey and 51 per 
cent into cheese as an average of factory milk. 
The followinsf arrangfement shows the extent of 



average monthly variation 



season 



during 



the factory 



CHEESE-PRODUCING SOLIDS AND WHEY SOLIDS IN 
CHEESE-FACTORY MILK 



Month 


Percentage of cheese- 
producing solids in milk 


Percentage of whey- 
solids in milk 




Lowest 


Highest 


Average 


Lowest 


Highest 


Average 


April 

May 

June 

July 

August 

September.. . 
October 


5.75 
5.68 
6.06 
6.01 
6.09 
6.27 
7.02 


6.14 
6.91 
6.61 
6.60 
6.76 
7.14 
7.69 


5.97 
6.17 
6.36 
6.30 
6.48 
6.78 
7.29 


5.94 
6.11 
6.17 
6.10 
6.06 
5.86 
5.96 


6.09 
7.78 
6.44 
6.47 
6.35 
6.26 
6.44 


6.01 
6.26 
6.28 
6.22 
6.17 
6.08 
6.21 



Expressing the relations of the general averages 
in the preceding table in the form of percentages of 
milk-solids, we have the following table: 







Percentage of total 


Percentage of total 




Pounds of milk- 


solids of milk in 


solids in milk in 


Month 


solids m 100 


form of cheese- 


form of whey- 




pounds of milk 


producing solids 


solids 


April 


11.98 


49.8 


50.2 


May 


12.43 


49.6 


50.4 


June 

July 


12.64 


50.3 


49.7 


12.52 


50.3 


49.7 


August 


12.65 


51.2 


48.8 


September . 


12.86 


52.7 


47.3 


October. . . . 


13.50 


54.0 


46.0 



We see a general tendency for the cheese-producing 
solids in milk to increase during the factory season, 



MILK AND YIELD OF CHEESE 



203 



which is only another way of saying that the per- 
centage of fat and of casein increases with advance 
of lactation. 

Before leaving this phase of the subject, it will 
be found interesting to compare the ratio of cheese- 
producing solids and whey-solids in rnilk varying 
considerably in percentage of fat. From the figures 
in the following table, it is very strikingly shown 
that in normal milk rich in fat a very much larger 
proportion of the milk-solids goes into cheese and 
correspondingly less into whey, than in the case of 
milk poorer in fat. 



CHEESE-PRODUCING SOLIDS AND WHEY SOLIDS IN 
RICH AND POOR MILK 







Per cent 


Per cent 


Per cent of 


Per cent of 


Per cent 


Per cent 


of cheese- 


of whey 


solids in form 


solids in form 


of solids 


of fat 


producing 


solids 


of cheese- 


of whey- 






solids 




solids 


solids 


11.80 


3.26 


5.71 


6.09 


48.4 


51.6 


12.65 


3.76 


6.89 


5.76 


54.5 


45.5 


12.75 


4.01 


6.47 


6.28 


50.7 


49.3 


14.30 


4.28 


7.32 


6.98 


51.1 


48.9 


14.50 


4.89 


8.24 


6.26 


56.9 


43.1 


14.90 


5.38 


8.54 


6.36 


57.3 


42.7 


15.40 


5.78 


9.06 


6.34 


58.8 


41.2 



DISTRIBUTION OF MILK CONSTITUENTS 
IN WHEY AND CHEESE 

Having learned what the principal losses of 
cheese-producing solids are, we will next show by 
illustrations in what amounts the different constit- 
uents of milk are divided between whey and 
cheese in cheese-making. The following results 
are based on average losses of milk constituents. 



204 SCIENCE AND PRACTICE OF CHEESE-MAKING 

The cheese is assumed to contain 37 per cent of 
water, about 5 per cent of salts and no allowance 
is made for mechanical losses other than as indi- 
cated 







Water 


Milk- 
solids 


Fat 


Casein 


Albumin 


Sugar, 
ash, etc. 


I. 

Milk... 
Whey.. 
Cheese 


Pounds 

100.00 

91.70 

8.30 


Pounds 

88.60 

85.55 

3.05 


Pounds 

11.40 

6.15 

5.25 


Pounds 
3:00 
0.21 
2.79 


Pounds 
2.10 
0.10 
2.00 


Pounds 
0.60 
0.57 
0.03 


Pounds 
5.70 
5.27 
0.43 


II. 

Milk... 
Whey.. 
Cheese 


100.00 
89.40 
10.60 


87.00 

83.10 

3.90 


13.00 
6.30 
6.70^ 


4.00 
0.28 
3.72 


2.50 
0.10 
2.40 


0.70 
0.67 
0.03 


5.80 
5.25 
0.55 


III. 

Milk... 
Whey.. 
Cheese 


100.00 
87.10 
12.90 


85.50 

80.75 

4.75 


14.50 
6.35 
8.15 


5.00 
0.35 
4.65 


2.90 
0.10 
2.80 


0.75 
0.72 
0.03 


S.85 
5.18 
0.67 



In connection with this table, study Figs. 34, 35 
and ^6. 

RELATION OF MILK-FAT TO CHEESE 

YIELD 

Much study has been given, especially in New 
York, to the quantitative relations existing between 
the percentage of fat in milk and the yield of cheese, 
or the amount of cheese corresponding to one pound 
of fat in milk. The relation is a very simple one to 
calculate and is found by dividing the number of 
pounds of cheese made from 100 pounds of milk by 
the number representing the per cent of fat in milk. 
For example, the yield of cheese from 100 pounds 
of milk containing 3 per cent of fat is 8.31 pounds; 



MILK AND YIELD OF CHEESE 205 

the ratio of milk-fat to cheese yield is, therefore, 
8.31-^-3, which equals 2..'jy; that is, in this case, one 
pound of fat in milk is equivalent to 2.77 pounds of 
cheese. In the case of milk containing 4 per cent of 
fat and producing 10.60 pounds of cheese for 100 
pounds of milk, each pound of fat in milk is equiva- 
lent to 2.65 pounds of cheese. 

The study of this relation was first undertaken at 
the New York experiment station to ascertain 
whether a pound of fat in all normal milks is 
equivalent to the same amount of cheese. The 
bearing of this point upon the use of fat in milk as 
a basis of paying for milk at cheese-factories is 
obvious. If a pound of fat in milk were always 
equivalent to the same amount of cheese, then no 
question could arise as to the strict accuracy of a 
milk- fat basis in making dividends. If the amount 
of cheese made for a pound of fat in milk varies, 
then the fat could not be regarded as a strictly ac- 
curate measure of cheese yield, and other points than 
yield would need to be considered, such as the quality 
of the cheese, in measuring the value of milk for 
cheese-making. The details of the subject of methods 
of paying for milk at cheese-factories will be con- 
sidered later (p. 253). 

We have already seen that the yield of cheese 
Is chiefly dependent upon two constituents of milk, 
casein as well as fat. It is obvious that if fat and 
casein were always present In milk In the same 
relative proportions, then the yield of cheese would 
always be in the same uniform ratio to milk- fat. 
But we have found (p. 164) that the ratio of fat 
and casein In milk varies considerably and, for 



206 SCIENCE AND PRACTICE OF CHEESE-MAKING 



this reason, the ratio of milk-fat to yield of cheese 
must also vary. It is a matter of practical interest 
and importance to know what the extent of such 
variations may be. 



600 
IS. 20 






va.QQ 



-Si^.O 




5i.9-D- 



3 J 05 



S.JQ. _ 



_,_;!aL35^ 



_ 3^5.5 



S'^O 



itttiiiiii 







WATER. 

{xnd. 
6AUT5 



.-^Uiiii iiliffi 



■'M4§. 



PRDTE1N5 



FAT 



FIG. 36 — YIELD AND CONSTITUENTS OF CHEESE FROM 100 

POUNDS OF MILK CONTAINING AMOUNTS OF FAT 

VARYING FROM 0.10 PER CENT (SEPARATOR SKIM- 

MILK) up to 6.00 PER CENT. 

The figures Immediately above each column give the numher of pounds of 
cheese (containing 37 per cent of water) made from 100 pounds of milk. The 
figures within the diagram give the pounds of each constituent in the cheese. 
The figures at the extreme top of the diagram indicate percentages of fat m 
milk. 

Taking milk as it averages, we find the following 
variation of relation between fat and cheese yield in 
normal milks containing different amounts of fat. 
The cheese yield is based on a uniform percentage 
of water in the cheese, 37 per cent. 



MILK AND YIELD OF CHEESE 



207 



RATIO OF FAT TO CHEESE YIELD IN NORMAL MILK 









■ 
Pounds of cheese 


Per cent of 


Per cent of 


Pounds of cheese 


made for each 


fat in milk 


casein in milk 


made from 100 
pounds of milk 


pound of fat 
in milk 


3.00 


2.10 


8.30 


2.77 


3.25 


2.20 


8.88 


2.73 


3.50 


2.30 


9.45 


2.70 


. 3.75 


2.40 


10.03 


2.67 


4.00 


2.50 


10.60 


2.65 


4.25 


2.60 


11.17 


2.63 


4.50 


2.70 


11.74 


2.61 


4.75 


2.80 


12.31 


2.59 


5.00 


2.90 


12.90 


2.58 



In our study of the ratio of fat and casein in 
milk (p. 164), it was seen that the casein does not 
increase as rapidly as fat does, and that, therefore, 
milk richer in fat usually contains less casein in 
proportion to fat than does milk less rich in fat. 
In harmony with this condition, and as a result of 
it, the amount of cheese made for a pound of milk- 
fat decreases as the percentage of fat in milk 
increases. This is clearly shown in the preceding 
table. 

An interesting fact shown in this table is that 
the rate of decrease of the ratio of fat to cheese 
yield is less rapid as the percentage of fat in milk 
increases. Thus, in the case of milks containing 
3 and 3.25 per cent of fat, the decrease of cheese 
yield in relation to fat is from 2.yy to 2.^^^, a differ- 
ence of 0.04 pound ; between 3.25 and 3.50, and also 
between 3.50 and 3.75, the decrease is 0.03; for 
each 0.25 per cent of increase of milk-fat from 
3.75 to 4.75 per cent, the decrease in the ratio is 
only 0.02; and between 4.75 and 5.00 per cent, 
the decrease is only o.oi. This is explained by the 



208 SCIENCE AND PRACTICE OF CHEESE-MAKING 

fact, already emphasized (p. 190), that in the case 
of milk rich in fat, a smaller proportion of the fat 
is lost in cheese-making than in the case of milk 
poorer in fat. 



PER CENT. OF FAT IN MILK AND YIELD Of CHEESE 




FIG. 37 — DIAGRAM SHOWING YIELD AND CONSTITUENTS OF 

CHEESE FROM 100 POUNDS OF MILK OF DIFFERENT BREEDS 

OF DAIRY cows 

The figures inimediately above each column give the number of pounds 
of cheese (containing 37 i)er cent of water) made from 100 poimds of milk. The 
figures in the diagram give the pounds of each constituent in the cheese. The 
figures at the top of the diagram indicate percentage of fat in milk. 

In this connection, it will be interesting to observe 
how the matter works out when applied in the case 
of the milk of different breeds of cows. 



MILK AND YIELD OF CHEESE 



209 



RATIO OF FAT TO CHEESE YIELD IN MILK OF DIFFERENT 

BREEDS 



Breed 


Per cent 

of fat 

in milk 


Per cent 

of casein 

in milk 


Pounds of 

cheese made 

for 100 

pounds 

of milk 


Pounds of 
cheese made 

for each 

pound of fat 

in milk 


Holstein-Friesian 

Ayrshire 


3.26 
3.76 
4.01 
4.28 
4.89 
5.38 
5.78 


2.20 
2.46 
2.63 
2.79 
3.10 
2.91 
3.03 


8.90 

10.14 
10.82 
11.52 
13.02 
13.51 
14.36 


2.73 
2.70 


American Holderness.. . 
Shortliorn 


2.70 
2.70 


Devon 


2.66 


Guernsey 


2.51 


Jersey 


2.49 







Before closing- our discussion of this subject, we 
wish to call attention to the fallacy that may be 
introduced by wide variations in the water content 
of cheese, when we are making a comparison of the 
yield of cheese with reference to the milk-fat. For 
example, 100 pounds of milk containing 4 per cent 
of fat may be made into cheese with a yield of 10.40 
pounds in one case, and 11.00 pounds in another, 
the difference being due wholly to water. In one 
case the yield is 2.60 pounds for one pound of milk- 
fat; in the other, it is 2.75 pounds. It is thus seen 
that, when such comparisons are to be made with 
reference to the relation of fat to yield of cheese, 
the cheese should contain the same percentage of 
water. The table on page 199 well illustrates the 
variations of yield in relation to water. If we use 
the results there given as a basis for calculating 
the yield of cheese in relation to milk-fat, we find 
that the amount of cheese made for one pound of 
milk-fat varies from 2.51 to 3. 11, when we take the 
factory yield, with its great variation of water; but, 



2IO SCIENCE AND PRACTICE OF CHEESE-MAKING 

if the calculation is based on cheese containing the 
same percentage of water, the cheese yield varies 
in relation to fat only from 2.61 to 2.89. This is a 
much narrower range and represents such variations 
as are properly due to differences in composition of 
milk. 



CHAPTER XVIII 

Methods of Calculating Yield of Cheese 

In the chapter preceding, we have seen that fat 
and casein in milk furnish most of the solid mate- 
rial which we find in cheese ; we have also seen that 
certain amounts of fat and of casein are inevitably 
lost in whey during the operations of cheese-mak- 
ing; and we have further seen that the amount of 
water in cheese may be made to vary largely or 
may be held within comparatively narrow limits, 
being controlled by the conditions used in the 
process of cheese-making. From our preceding 
discussion, it might seem that the relations between 
composition of cheese and yield of milk were suf- 
ficiently understood to enable us to calculate the 
amount of cheese yield when the percentages of fat 
and of casein in milk are known, or even when the 
fat alone is given. As a matter of fact, several 
different methods have been proposed and have 
been employed in studying problems of cheese 
yield. There is an advantage in having some fairly 
reliable method for ascertaining the amount of 
cheese that can be made from lOO pounds of milk. 
Results thus obtained afford a basis of comparison 
with actual results. A cheese-maker can, by such 
means, ascertain if his losses in cheese-making are 
excessive or if he is retaining too much or too little 
water in cheese. 



212 SCIENCE AND PRACTICE OF CHEESE-MAKING 

The different methods of calculating cheese yield 
which have been in use have never been carefully 
compared in such a way as to show their relative 
accuracy or value. It has seemed desirable that such 
a study should be made, and it is now our purpose 
to take up for consideration the various methods 
referred to. We shall discuss, in the case of each 
method, their underlying principles, indicate the 
points of fundamental weakness, and give the results 
of an exhaustive comparative study, based upon an 
application of each method to 200 experiments in 
cheese-making, using for this purpose the work done 
at the New York experiment station, which appears 
to offer the only material sufficiently complete to be 
available for such an investigation. 

The methods which have been proposed for use 
in calculating the amount of green cheese are the 
following : 

(i) The use of the percentage of fat in milk, 
which, expressed as a formula, is : 
Yield of cheese=2.7 Fat. 

(2) The use of the percentage of fat in milk and, 
in addition, a constant factor. This, expressed as a 
formula, is : 

Yield of cheese=i.i Fat-l-5.9. 

(3) The use of the percentage of fat and of 
casein, which can be expressed in the following 
form : , 

Yield of cheese:^:. I Fat-l-2.5 Casein. 

(4) The use of the percentage of fat in milk and 
of the solids-not-fat. This is somewhat more com- 
plicated and is expressed thus : 

17-- ij e 1 /Solids-not-fat „„^ x, \ ^ -„ 
Yield of cheese— I + 0.91 Fat I x 1.58 



/ Solic 

=1 — 



CALCULATING YIELD OF CHEESE 213 

(5) A new method based on the use of the per- 
centage of fat and the percentage of casein (either 
actual or calculated). The general formula for this 
method is as follows : 

,^. ,j ^ , (Fat - 0.07 Fat + Casein - 0.10) X 1.09 

Yield of cheese= 



1.00 — Water in cheese (expressed as hundredths) 

As will be pointed out later, this can be much 
simplified, becoming 

Yield of cheese=(Fat4-Casein) X1.63 
hi the case of cheese containing a uniform amount of 
water (^^y per cent). When only the fat is known and 
the casein is calculated from the formula on p. 170 
the formula for both casein calculation and calcu- 
lation of cheese yield is simplified into one : 

(6) Yield of cheese:=2.3 Fat+i.4. 

These last formulas, based upon results of New 
York experiment station work, are now published for 
the first time. 

Before giving the detailed results of our com- 
parative study of these different methods, we will 
discuss each one separately, explaining underlying 
principles and thus learning how the methods came 
to be suggested. 

METHOD BASED ON RELATION OF FAT TO 
YIELD OF CHEESE (i) 

The basis of this method has been discussed in 
the chapter preceding. In the investigations carried 
on at the New York experiment station, covering 
all varieties of factory conditions, it was found that 
when the yield of cheese for 100 pounds of milk was 
divided by the number representing the percentage 
of fat in milk, the averages, season by season, and 



214 SCIENCE AND PRACTICE OF CHEESE-MAKING 

factory by factory, were very uniform, being very 
close to 2.y2 pounds of cheese for one pound of fat 
in milk. The individual results giving the average 
varied widely, from 2.51 to 3. 11. These extreme 
variations were due to wide variations in the water 
content of the cheese rather than to variation in 
the real relation of fat to cheese yield proper, as 
we have pointed out in the chapter preceding. Based 
on a uniform percentage of water in cheese, the va- 
riations would be within much less wide limits, 
ranging from 2.61 to 2.89. This variation was due 
mainly to variation in the relation of the fat and 
casein in the milk and, in some cases, to excessive 
losses experienced in the process of cheese-making. 
The average result {2.y) is based upon milk con- 
taining 3.75 per cent of fat, 2.46 per cent of casein 
and upon cheese containing nearly 37 per cent of 
water. The ratio of milk-fat to casein is, therefore, 
I :o.665. When the ratio of fat and casein varies 
widely from this, we shall get more or less cheese 
than that called for by the rule. Thus, in milk in 
which the casein is high in relation to fat, as often 
happens in milk low in fat, the formula gives too 
low results (p. 207) ; while the reverse is true in 
case of milk high in fat in relation to casein, as 
often happens in milk rich in fat (p. 214). There- 
fore, as a result of the variations of the relation of 
fat and casein in cheese-factory milks, we may ex- 
pect this method to give results varying from the 
actual yield of cheese, in extreme and uncommon 
cases, to an extent equal to 0.5 to 0.75 pound of 
cheese for 100 pounds of milk. When the variation 
is greater than this, it is usually due to excessive or 
deficient amounts of water in cheese. 



CALCULATING YIELD OF CHEESE 215 

METHOD BASED ON FAT IN MILK AND A 
FIXED NUMBER ADDED (2) 

This method, stated in the form of a rule, is as 
follows : Multiply the number representing the 
per cent of fat in milk by i.i and to the result add 
5.9. This formula was worked out at the Wiscon- 
sin experiment station and is based upon certain 
facts which will be briefly considered. One pound 
of milk- fat in butter can readily hold about 0.18 
pound of water and it can just as readily hold the 
same amount in cheese. We multiply the per cent 
of fat in milk by i.i instead of 1.18, because not all 
of the milk-fat goes into the cheese. To illustrate, 
take milk containing 4 per cent of fat ; in cheese- 
making, about 3.72 pounds of this fat in 100 pounds 
of milk goes into cheese. This figure, multiplied 
by 1. 1 8, equals nearly 4.40, the same as 4 multiplied 
by I.I. In other words, the amount of fat that 
actually goes into cheese multiplied by 1.18 gives 
about the same result as the amount (per cent) of 
fat in milk multiplied by i.i. 

The next question that presents itself is as to 
why we add the particular number 5.9 to the fat 
multiplied by i.i. This figure is based upon the 
amount of cheese that can be made from 100 pounds 
of separator skim-milk of average composition, and 
is supposed to account for the milk-casein, the in- 
soluble salts and the moisture not provided foi in 
the milk-fat. It is in reality taking account of 
casein in milk, but only of the same amount for all 
milks. 

The inherent weak points of this method are the 
following: (i) In the case of excessive losses of 



2l6 SCIENCE AND PRACTICE OF CHEESE-MAKING 

fat ill cheese-making, the result found by multi- 
plying milk-fat by i.i is too high. (2) The estimate 
of 5.9 pounds as the measure of the cheese-making 
value of casein in skim-milk is based upon skim- 
milk of average composition. Therefore, in milk 
low in percentage of casein, 5.9 is too high, while 
in milk high in casein, the figure is too low. The 
method is faulty in that its accuracy depends upon 
a uniform percentage of casein in all milks, and we 
know that there are quite wide variations. 

METHOD BASED ON FAT AND CASEIN IN 

MILK (3) 

This method of finding the yield of cheese, stated 
in the form of a rule, is as follows : Multiply the 
number representing the per cent of fat in milk 
by I.I, and to this add the result obtained in multi- 
plying by 2.5 the number representing the per cent 
of casein in milk. This formula was originally 
worked out at the Wisconsin experiment station and 
was first extensively applied and confirmed by the 
work of the New York experiment station. 

This method is based upon the following facts: 
(i) Milk- fat is capable of holding mechanically 
one-tenth of its own weight of water. This has 
been already explained in detail in connection with 
the discussion of method 2. (2) The reason for mul- 
tiplying the amount of casein in milk by 2.5 is 
found in the yield of cheese from skim-milk and 
also in the results of some experimental work done 
at the New York experiment station. A prepara- 
tion of pure casein was made, dried, and then al- 
lowed to absorb as much water as it would be 



CALCULATING YIELD OF CHEESE 21/ 

likely to hold in being made into green cheese. It 
was found that one pound of casein takes up water 
enough to increase its weight to 2.25 pounds. If 
to this is added the amount of ash constituents 
taken up in the same amount of cheese, the weight 
is increased to just about 2.5 pounds. This method 
has the following defects : ( i ) As already pointed 
out, the calculation of the amount of cheese yield 
coming from milk-fat is too high when there are 
abnormal losses of fat in cheese-making. (2) 
When the yield of cheese is calculated by this 
method, the percentage of water in cheese is not 
uniform, but varies with the percentage of casein 
in milk, because the water content of the cheese is 
made dependent largely upon the amount of casein. 
The inevitable result is that in case of milks 
containing high percentages of casein in relation to 
fat, the percentage of water is greater in the cheese 
calculated by this method than in case of cheese 
from milks in which the amount of casein is lower 
in relation to fat. When the ratio of fat and casein 
is fairly constant, the results are quite satisfactory. 
The manner in which this method of calculation 
favors the yield of cheese in case of milk low in fat 
and relatively high in casein as against the yield 
of cheese in case of milk high in fat and relatively 
low in casein can be illustrated by the data in the 
table on the next page. 

Attention is called to the following facts in 
connection with the data contained in this table: 
(i) When the cheese made from the two differ- 
ent milks contains the same amount of water (37 
per cent), the water in the cheese made from 100 
pounds of milk amounts to 3.31 pounds in the case 



2l8 SCIENCE AND PRACTICE OF CHEESE-MAKING 



of the cheese made from the poorer milk and 5.31 
pounds in the case of the cheese made from the 
richer milk. When the cheese from the two milks 
is made to contain the average amount of water 
(37 per cent) found in green cheese, there is a 
normal difference of 2 pounds of water in the 
cheese made from 100 pounds of milk. What do 
we find in regard to the yield of cheese and of 
water in the cheese, when the yield of cheese is 
calculated by method 3? The yield of cheese from 
100 pounds of the poorer milk is increased 0.19 
pound, from 8.90 to 9.09 pounds, an increase wholly 







Pounds of 














cheese 


Pounds 


Pounds of 


Pounds of 




Per cent 


Per cent 


(containing 


of water 


cheese for 


water in 


Per cent of 


of fat 


of 


37 per cent 


in cheese 


100 pounds 


cheese 


water in 


in 


casein 


of water) 


made 


of milk 


from 100 


cheese cal- 


milk 


in milk 


made for 


from 100 


calculated 


pounds of 


culated by 






100 pounds 
of milk 


pounds 


^y , 


milk 


method 3 






of milk 


method 3 


(method 3) 




3.26 


2.20 


8.90 


3.31 


9.09 


3.50 


38.50 


5.78 


3.03 


14.36 


5.31 


13.93 


4.88 


35.00 



due to the greater amount of water contained in 
the cheese; the water increases from 3.31 to 3.50 
pounds, and the percentage of water in the cheese, 
from 37 to 38.50. In the case of the cheese made 
from the richer milk, the reverse is found to be 
true. The yield of cheese containing 37 per 
cent of water is 14.36 pounds for 100 pounds of 
milk, and this is decreased 0.43 pound or from 
14.36 to 13.93 pounds. This decrease is wholly 
due to the smaller amount of water in the cheese 
when the yield is calculated by method 3. Thus, 
the amount of water in the cheese containing 37 



CALCULATING YIELD OF CHEESE 2ig 

per cent of water is decreased from 5.31 to 4.88 
pounds in the cheese calculated by method 3, and 
the percentage of water from 37 to 35 per cent. 
We see, therefore, that the difference of cheese 
yield in these two cases should be normally 5.46 
pounds for the cheese made from 100 pounds of 
milk, but the difference is only 4.86 pounds, or 
0.62 pound too small, when the yield is calculated 
by method 3. (3) Another objection raised to 
this method is that, under ordinary conditions, the 
percentage of casein in milk is not known and the 
method is consequently inapplicable. In reply to 
this, the percentage of casein in milk can be calcu- 
lated from the percentage of milk-fat and the method 
carried out in the usual way. Even when the amount 
of casein in milk is calculated, the results are gen- 
erally much more accurate than those given by method 
2 (i.i Fat+5.9). 

METHOD BASED ON FAT AND SOLIDS- 
NOT-FAT IN MILK (4) 

In the twelfth annual report of the Wisconsin 
experiment station there is a detailed discussion of 
the facts leading to the proposal of the following 
formula : 

Yield of green cheese containing 37 per cent of 
water= 

^Solids-not-fat ^. 0.9 1 Fat ) X 1.58 

This formula is based on the following details: (i) 
The amount of solids-not-fat in loo pounds of milk, 
divided by 3, represents the amount of milk-solids, 
other than fat, available for cheese, including added 



220 SCIENCE AND PRACTICE OF CHEESE-MAKING 

salt ill cheese; it therefore inckides milk-casein and 
ash constituents. (2) The average amount of fat 
lost in cheese-making is taken as 9 per cent of the 
milk- fat and, consequently, 0.91 of the milk-fat is 
calculated as being in the cheese. (3) In using the 
factor 1.58, the cheese-solids are calculated to an 
equivalent amount of cheese containing 37 per cent 
of water. This method has been supposed to give 
more accurate results than any of the preceding 
methods. 

The following objections to the method suggest 
themselves : ( i ) It involves the accurate determina- 
tion of the specific gravity of milk in addition to 
the percentage of milk-fat. This ought not to be 
a serious objection, but is found to be so practically 
when cheese-makers try to find time to take the 
necessary lactometer readings. (2) The formula is, 
more complicated than any other, requiring more 
extended arithmetical work, although entirely of a 
simple kind. (3) The accuracy of calculating the 
non-fat cheese-solids as equal to one-third of the 
solids-not-fat of milk is not as close as is desirable, 
because, when applied in the case of different milks, 
the results are found to be quite irregular outside 
of certain limits, to which attention will be called 
later. 

NEW METHOD BASED ON FAT AND 
CASEIN IN MILK (5) 

On account of dif^culties experienced in applying 
the methods under consideration with uniform and 
accurate results, an effort has been made, based on 



CALCULATING YIELD OF CHEESE 221 

the results of the work done at the New York ex- 
periment station, to work out a method of deter- 
mining cheese yield which should be simple and 
at the same time more accurate than the methods 
previously used. This method is based upon (i) 
the per cent of fat and of casein in milk; (2) a loss 
of fat proportional to the amount of fat in milk, 
based upon average results; (3) a uniform loss of 
casein; (4) an amount of salts and albumin in cheese 
proportional to the available fat and casein in 
the milk; and (5) a uniform percentage of water in 
cheese. 

We will now briefly consider the details upon 
which the method is based, under the two following 
divisions: (i) Calculation of cheese-solids, and (2) 
calculation of water in cheese. The amount of 
solids in cheese is calculated by the formula, 
(o.93Fat+Casein — 0.10X1-09. This is based upon 
the following details: (i) Of the fat in milk, 7 per 
cent (0.07 pound for each pound of milk-fat) is lost 
in whey and 93 per cent (0.93 pound for each 
pound of milk-fat) remains in cheese (p. 190). 
(2) Of the milk-casein, about o.io pound for 100 
pounds of milk is lost, the rest going into the 
cheese (p. 195). (3) The other constituents of 
cheese-solids, consisting mostly of salts (p. 187), 
form about 9 per cent (0.09) of the fat and casein 
present in cheese. Therefore, if we multiply the 
amount of fat and casein in cheese by 1.09 we ob- 
tain the total amount of cheese-solids (fat, casein, 
salts, etc.) in cheese. For example, suppose we have 
milk containing 4 per cent of fat and 2.5 per cent of 
casein, how many pounds of cheese-solids can be 



222 SCIENCE AND PKACTICE OF CHEESE-MAKING 

made from lOO pounds of such milk? Using the 
formula, we have [0.93X4 (f at) +2.5 (casein) — 
o.io]Xi.09=(3.72+24o)X 1.09=6.67 pounds. 

(4) It remains now simply to calculate the cheese- 
solids into cheese with a given percentage of water. 
This can be done by subtracting from i.oo the per- 
centage of water desired in the cheese, expressed as 
hundredths, and then dividing by the result the solids 
in the cheese, as obtained above. The formula, thus 
amended, becomes: 

(0.93 Fat + Casein - 0.10) x 1.09 

100 — W (water in cheese) 

Continuing the illustration in which we have found 
6.6y pounds of cheese-solids, we will suppose that we 
wish to know how much cheese, containing 37 per 
cent of water, can be made from this amount of 
cheese-solids. We simply divide 6.67 by 0.63 (i.oo — 
0.37), which gives 10.6 pounds. To find the equiv- 
alent amount of cheese containing 35 per cent of 
water, divide by 65 (i.oo — 0.35) ; for cheese con- 
taining 40 per cent of water, divide cheese-solids by 
0.60 (i.oo — 040). 

If, then, we wish to have a method for calculating 
yield of cheese when the cheese contains a definite 
amount of water, say 37 per cent, which is the average 
amount in green cheddar cheese, we can use the- 
formula : 

(0.93 Fat + Casein - 0.10) X 1.09 



0.63 

This can be further simplified by dividing 1.09 by 
0.63, when the formula becomes 

(0.93 Fat-f Casein — o. 10) X 1.73. 
In other words, find, in the manner Indicated, the 



CALCULATING YIELD OF CHEESE 223 

amount of fat and casein that go into the cheese and 
multiply by 1.73. 

After satisfactorily applying the formula in this 
form to a large number of cases, it occurred that 
this might be used as a means of working out a 
still simpler relation between the fat and casein 
of milk and yield of cheese. Using the foregoing 
formula for calculating the cheese yield with milks 
covering quite a wide variation in percentages of fat 
and of casein, it was found that the formula could be 
simplified to the following form : 

(5) (Fat-|-casein)Xi-63^yield of cheese 
for 100 pounds of milk, the cheese containing 37 per 
cent of water. Stated in the form of a rule, this 
becomes : Add together the numbers representing the 
percentages of fat and of casein in milk and multiply 
the sum by 1.63. 

From this formula, we can calculate in the fol- 
lowing manner the equivalent amount of cheese 
containing any percentage of moisture. Multiply 
the cheese yield, calculated according to the last 
formula, by 0.37; subtract this amount from the 
weight of cheese and divide the remainder by i.oo 
minus the number expressing the desired percent- 
age of moisture. Expressed as a formula, this 
becomes : 

P (Number of pounds of cheese) — 0.37 P 

100 — W (percentage of water desired^ 

For convenience, we have thus calculated a fac- 
tor which can be used directly in determining 
cheese yield for each percentage of water from 30 
to 50. 



224 SCIENCE AND PRACTICE OF CHEESE-MAKING 

SIMPLE METHOD OF CALCULATING 
CHEESE YIELD FOR CHEESE CON- 
TAINING DIFFERENT PERCENT- 
AGES OF WATER 

In order to obtain the amount of cheese yield con- 
taining a given percentage of water, substitute the 
number opposite the given percentage in the following 
list for 1.63 in the last formula above given, which 
would then become : 

Yield= (Fat+ Casein) XN 
(N being the number in the following list which cor- 
responds to the percentage of water in cheese desired). 

Per cent of water _ Factor to be used 

in cheese as N in formvila (Fat + casein) x N 

30 1.47 

31 1.49 

32 1.51 

33 1.53 

34 1.555 

35 1.58 

36 1.605 

37 1.63 

38 1.655 

39 1.68 

40 1.71 

41 1.74 

42 1.77 

43 1.80 

44 1.835 

45 1.87 

46 1.90 

47 1.94 

48 1.98 

49 2.015 

50 2.05 

SIMPLE METHOD FOR CALCULATING 

YIELD OF CHEESE FROM FAT AND 

CALCULATED CASEIN 

In connection with the foregoing method, which 
is based in part upon the percentage of casein in 
milk, it may be objected that the method cannot be 



CALCULATING YIELD OF CHEESE 225 

applied when we do not know the percentage of 
milk-casein. In reply to this, it can be stated that 
fairly accurate results can be obtained by calculat- 
ing the amount of casein in milk from the formula: 
Per cent of casein in milk=(Fat — 3)Xo.4+2.i 
(p. 170). 

This formula can be combined with the follow- 
ing formula: Cheese yield=(Fat+Casein) Xi-63 
and the two operations of calculating casein and 
cheese yield can be combined in one simple formula, 
as follows : 

(6) Cheese yield=2.3F-(-i.4. 

Therefore, in multiplying the per cent of fat in milk 
by 2.;^ and adding 1.4 to the result, we obtain directly 
the yield of cheese, containing 37 per cent of water, 
based on the percentage of milk-fat and the amount 
of casein corresponding to this percentage of fat, as 
found by the milk-casein formula. 

The yield of cheese corresponding to any per- 
centage of water from 30 to 50 can be similarly cal- 
culated. This is done by substituting for N in the 
following formula one of the numbers in the last table 
preceding, according to the desired percentage of 
water: (1.4 Fat+o.9)XN. 

METHOD OF CALCULATING YIELD OF 
RIPE CHEESE 

The variation in. the amount of moisture in cheese 
when it is sold for consumption necessarily varies 
with a number of different conditions (p. 45) and 
an effort to estimate the amount of cheese yield in 
marketable condition is, to some extent, a matter 
of guesswork, unless one knows something of the 



226 SCIENCE AND PRACTICE OF CHEESE-MAKING 

conditions of temperature, moisture, etc., under 
which the cheese has been kept. However, it is 
sometimes desired to know approximately the yield 
of ripened cheese. We can assume (i) that the 
green cheese contains an average percentage of 
water (^y) and (2) that it loses 5 pounds of water 
for 100 pounds of cheese. This would have the 
effect of reducing the percentage of water in the 
ripe cheese to. about 34. Therefore, the simplest way 
to calculate the amount of ripe cheese, if the com- 
position of the milk is known, is to multiply the sum 
of the percentage of fat and casein in milk by 1.555, 
or, expressed as a formula : 

Yield of ripe cheese for 100 pounds of milk=: 
(Fat+Casein)X 1.555- 

COMPARISON OF ACCURACY OF DIF- 
FERENT METHODS OF CALCULAT- 
ING CHEESE YIELD 

In making a comparative study of the accuracy 
of the different methods that have been used or 
proposed for calculating yield of cheese, the follow- 
ing procedure was adopted : As a basis upon which 
to work, there were taken 200 of the experiments 
contained in the records of the New York experi- 
ment station, which give full analyses of milk, 
whey and cheese, and yields of cheese. The yields 
of cheese as given were calculated to a uniform 
basis of cheese containing ^y per cent of water. 
The yield of cheese was then calculated according 
to each one of the formulas that have been discussed. 
In the case of the methods in which casein is a 



CALCULATING YIELD OF CHEESE 22/ 

factor, the yield of cheese was calculated both for 
the actual amount of casein in the milk as obtained 
by analysis and for the calculated amount of casein 
as obtained by the casein formula. There were 
thus compared, in reality, seven different methods. 
It is impracticable to give these results in detail, 
but it will be found sufficient to present them in 
the form of tabulated summaries. It has been 
found that the most effective means of compari- 
son is to divide the experiments into several 
groups based on the percentage of fat in milk, and 
under each group to indicate the number of cases 
in which the results differ, within certain limits, 
from the actual yield of cheese. To illustrate, we 
will take Group I (p. 228), including 22 experiments, 
in which milk containing 3 to 3.49 per cent of fat was 
used. In the case of method i ( Fat X 2.7), there are 
20 cases out of the 22 in which the calculated yield 
of cheese is within 0.25 pound (4 ounces) of the 
actual yield. There are 2 cases in which the calculated 
yield is within 0.26 to 0.35 pound of the actual yield. 
In the case of formula 2, there are only 5 cases in 
which the calculated yield is within a quarter of a 
pound of the actual yield, etc. 

A study of the table on page 228 enables one to 
observe the truth of the following statements: 

The different methods in some cases show great 
variation in respect to accuracy, according to the 
composition of the milk. Thus, method i (FatX 
2.7), which has usually been regarded as, perhaps, 
the least accurate of any method in use, is found 
to give most excellent results in the case of milks 



228 SCIENCE AND PRACTICE OF CHEESE-MAKING 



COMPARISON OF DIFFERENT METHODS FOR CALCULATING 

CHEESE YIELD 





1 


2 




3 


4 


5 


6 








1.1 Fat-1- 2.5 












0\ 


Casein 


CO 

to 
X 


.? .? 


'S 


Group I 








22 Exp'ts 




ir> 




3 S 


£" 




w § 




Fat 3-3.49% 
Variation 




+ 


"s.s 


On 
+ 


fo 


+ Ca 
1.63 

ual c£ 


from 


■y 


5'S 




ti 






CO "Ti 


actual yield 


rt 
fe 






U O 


w 
^ 


• 






0-0.25 lb. 


20 


5 


10 


11 


5 


19 


21 


0.26-0.35 lb. 


2 


2 


4 


9 


10 


2^ 


1 


0.36-0.50 lb. 




7 


7 


2 


5 


1 




0.51-0.75 lb. 




7 


1 





2 






0.76-1.00 lb. 




1 












Group II 
















59 Exp'ts 
















Fat 3.50-3.74 
















0-0.25 lb. 


34 


43 


43 


40 


48 


49 


29 


0.26-0.35 lb. 


10 


3 


12 


9 


7 


6 


13 


0.36-0.50 lb. 


8 


10 


3 


7 


1 


4 


9 


0.51-0.75 lb. 


7 


2 


1 


3 


3 




8 


Group III 
















51 Exp'ts 
















Fat 3.75-3.99 
















0-0.25 lb. 


33 


29 


35 


32 


38 


37 


31 


0.26-0.35 lb. 


8 


6 


3 


12 


7 


7 


10 


0.36-0.50 lb. 


9 


12 


6 


7 


5 


5 


9 


0.51-0.75 lb. 


1 


3 


6 




1 


2 


1 


0.75-0.99 lb. 






1 










Group IV 
















43 Exp'ts 
















Fat 4.0-4.19 
















0-0.25 lb. 


20 


8 


29 


27 


20 


35 


29 


0.26-0.35 lb. 


9 


13 


5 


3 


8 


4 


1 


0.36-0 50 lb. 


9 


9 


6 


4 


5 


3 


3 


0.51-0.75 lb. 


4 


4 


2 


6 


4 


I 


6 


0.75-0.99 lb. 


t 


5 


1 


3 


6 


^ ^ 


4 


1.00-1.50 lb. 


o 


7 












Group V 
















25 Exp'ts 
















Fat 4.2-4.4 
















0-0.25 lb. 


13 





16 


IS 


4 


20 


15 


0.26-0.35 lb. 


5 





4 


1 


4 


1 


1 


0.36-0.50 lb. 


5 


1 


2 


5 


8 


1 


4 


0.51-0.75 lb. 


2 


11 


2 


4 


7 


3 


5 


0.75-0.90 lb. 




4 


1 




2 


, , 




1.00-1.50 lb. 




9 













varying in fat from 3.0 to 3.50 per cent, and compara- 
tively fair results in the case of milks containing- fat 
up to 4.0 per cent. Method 2 (i.i Fat+5.9) gives 



CALCULATING YIELD OF CHEESE 229 

fairly good results in case of milks containing 3.50 
to 3.75 per cent of fat, because the casein of such 
milks is near the average upon which 1,his formula 
is really based (p. 215) ; but, outside of these nar- 
row limits, it is the least accurate of all the methods 
that have been used or proposed. In case of milk 
containing 4.0 per cent of fat or more, the method is 
entirely useless, in some cases varying from the 
real yield of cheese i to 1.5 pounds. Method 3 
(i.i Fat-|-2.5 Casein), when the actual amount of 
casein is known, gives rather poor results in case of 
milk below 3.5 per cent in fat, excellent results 
when the per cent of fat in milk ranges from 3.5 to 
4.0 per cent, fairly good results in case of milk con- 
taining as high as 4.2 per cent of fat, but less accurate 
with milks above this. Method 3, when the casein if 
calculated, gives results which are, in general, in ver^ 
good agreement with those obtained when the 
amount of casein is determined by chemical analysis. 
Method 4 

^^^-i^^lBSkM + 0.91 f)x 1.58, 

gives most excellent results when the milk con- 
tains 3.50 to 4.0 per cent of fat, but in other cases 
is, with the exception of method 2, the least accu- 
rate of any examined. This method has heretofore 
had the reputation of being, for all gTades of milk, 
the most accurate method in use. Method 5, when 
the per cent of casein in milk is known, is seen to 
be the most accurate method of all. When the 
casein is calculated, method 6 gives excellent com- 
parative results, the least satisfactory being in the 
case of milks containing 3.50 to 3.75 per cent of 



230 SCIENCE AND PRACTICE OF CHEESE-MAKING 

fat. In the case of milks containing 3 to 3.50 per 
cent of fat the results are most excellent. 

The following table gives a summary of the results, 
showing the percentage of cases in which the different 
methods are acc-tirate within the limits designated, 
taking all the 200 results into consideration without 
reference to special groups in respect to percentage 
of milk-fat : 











3 




5 


6 




1 


2 


Actual 


Calciolated 


4 


Actual 


Calculated 








casein 


casern 




casein 


casein 


0-0.25 


60. 


42.5 


66.5 


62.5 


57.5 


80 


62.5 


0.26-0.35 


17. 


12. 


14. 


17. 


18. 


10 


13. 


0.36-0.50 


15.5 


19.5 


12. 


12.5 


12. 


7 


12.5 


0.51-0.75 


7. 


13.5 


6. 


6.5 


8.5 


3 


10. 


0.76-0.99 


0.5 


4.5 


1.5 


1.5 


4. 





2. 


1.00-1.50 


0. 


8. 


0. 


0. 


0. 





0. 



From these results, the relative values of the dif- 
ferent formulas can be judged in a general, compara- 
tive way. It is evident that method 2 (i.i Fat-4-5.9) 
should not be used and that method 4, 

pHds|ot^fat^ .91 Fat) X 1.58 

should, if employed at all, be used only in the case 
of milks containing 3.5 to 4.0 per cent of fat. When 
the percentage of casein in milk is known, only 
method 5 (Fat-|-Casein) X1.63 should be used. In 
case the casein has to be calculated from the per- 
centage of fat in milk, then method 6 should be used. 
For ordinary purposes method 6 will probably be 
found to be the most useful, since the only factor 
needed is the percentage of milk-fat and the calcula- 
tion is extremely simple (2.3 Fat -(-1.4). 



CHAPTER XIX 

Milk Constituents in Relation to Compo- 
sition of Cheese 

While the yield of cheese from lOO pounds of milk 
depends, as has been shown (p. i86), upon the 
amount of fat, casein and insoluble salts in milk, so 
far as the cheese-solids are concerned, the percentage 
composition of the cheese-solids depends practically 
upon the relation of fat and casein in milk. Milk 
rich in fat, as compared with milk poor in fat, 
usually produces cheese containing more fat in pro- 
portion to other constituents. The composition of 
cheese depends primarily upon the composition 
of the milk used, provided the process of cheese-mak- 
ing is performed in a normal manner, so as to avoid 
excessive loss of fat or casein. In this connection 
we shall discuss the following points : (T ) The rela- 
tion of composition of milk to composition of 
cheese (a) in case of normal milk, (b) in case 
of skimmed milk, and (c) in case of milk containing 
added cream. (2) The United States standard for 
cheese. 

MILK CONSTITUENTS AND COMPOSITION 

OF CHEESE 

Composition of cheese from normal milk. — The 
composition of green cheese, in case of normal fac- 
tory milk, as made in New York state, shows the 

231 



2T^2 SCIENCE AND PRACTICE OF CHEESE-MAKING 

following range of variations and general average, 
as the result of the extended investigations carried on 
by the New York experiment station : 





Lowest 


Highest 


Average 


Water 


32.69 
56.11 
30.00 
20.80 
3.12 


43.89 
67.31 
36.79 
26.11 
7.02 


36.84 


Total solids 


63.16 


Fat.. 

Proteins 


33.83 
23.72 


Salts, etc. (represented in ash) 


5.61 


Percentage of solids in form of fat. . . 
Ratio of fat to proteins 


50.39 
1:0.79 


56.83 
1:0.63 


53.56 
1 :0 70 







We can illustrate differences in composition of 
cheese made from normal milk by taking cheese 
made from the milk of different breeds of cows. 
For this purpose, we will use the composition of 
milk as given on p. 165 in case of four different 
breeds : 



Breed 



Solids 

in 
cheese 



Fat in 
cheese 



Proteins 

in 

cheese 



Percentage 

of total solids 

in form 

of fat 



Ratio of 

fat to 
proteins 



Holstein-Friesian 

Ayrshire 

Guernsey 

Jersey 



Per cent 
63.00 
63.00 
63.00 
63.00 



Per cent 


Percent 


34.1 


23.6 


34.5 


23.3 


37.0 


20.8 


37.5 


20.4 



54.3 
54.8 
58.7 
60.0 



Fat: Proteins 
1: 0.69 
1: 0.67 
1; 0.56 
1: 0.54 



The difference in composition is very clearly 
seen, especially if we notice the percentage of 
the cheese-solids present in the form of fat and the 
ratio of fat to proteins as shown in the last two 
columns. In connection with this table, study Fig. 
37 (p. 208). 



MILK AND COMPOSITION OF CHEESE 



233 



The following table extends the illustration sys- 
tematically to ordinary milks containing- different 
percentages of fat. We may regard these as rep- 
resenting milks of different herds. See also Fig. 36. 



Per cent 

of fat 

in milk 



3.00 
3.25 
3.50 
3.75 
4.50 
4.25 
4.50 



Cheese- 
solids 



Fat in 
cheese 



Proteins 
in cheese 



Percentage 
of total 
solids in 

form of fat 



Ratic of 

fat to 
proteins 



Per cent 


Per cent 


Per cent 


63.00 


33.7 


24.1 




34.1 


23.7 




34.5 


23.3 




34.8 


23.0 




35.1 


22.7 




35.4 


22.4 




35.7 


22.1 



53.5 
54.0 
54.6 
55.2 
55.7 
56.2 
56.7 



Fat : Proteins 
1: 0.72 
0.70 
0.68 
0.66 
0.65 
0.63 
0.62 



These tables strikingly indicate that, as milk in- 
creases in percentage of fat, the cheese made from 
such milk increases in percentage of fat and de- 
creases in percentage of proteins. The composi- 
tion of the cheese-solids follows the composition of 
the milk as shown in the relation of fat and pro- 
teins. 

Composition of cheese made from skimmed 
milk. — The removal of fat from milk reduces the 
amount of fat in relation to casein, because, in 
skimming milk, only a relatively small amount of 
casein is removed with the fat. The remaining 
skim-milk is therefore richer in casein relative to 
fat, the ratio increasing with the amount of fat 
removed. The effect of skimming milk upon its 
composition and upon the composition of cheese 
is illustrated in the two followinsf tables. The 
data are based upon (i) normal milk containing 4 
per cent of fat, (2) removal of fat alone without 



234 SCIENCE AND PRACTICE OF CHEESE-MAKING 

other constituents, (3) a uniform percentage of 
casein in skim-milk, and (4) a uniform per cent (37) 
of water in cheese. While the data represent 
theoretical conditions, the results are not far from the 
truth in practical application and they serve satisfac 
torily to illustrate the point we desire to impress In 
connection with this table, study Fig. 38. 

EFFECT OF SKIMMING MILK ON COMPOSITION OF MILK 
AND YIELD OF CHEESE 



Pounds of fat 


Pounds of fat 


Pounds of 


Ratio of fat 


Pounds 


removed from 


left in 


casein m 


to casein 


of 


100 pounds 


skimmed 


skimmed 


in milk 


cheese 


of milk 


milk 


milk 












Fat: Casein 




ri)— 0.00 


4.00* 


2.50 




0.63 


10.60 


(2)— 0.50 


3.50 


2.50 




0.71 


9.79 


(3)— 1.00 


3.00 


2.50 




0.83 


8.98 


(4)— 2.00 


2.00 


2.50 




1.25 


7.37 


(5)— 3.00 


1.00 


2.50 




2.50 


5.71 


(6)— 3.90 


O.lOf 


2.50 




25.0 


4.33 



*Nonnal milk. tSeparator skim-milk. 



EFFECT OF SKIMMING MILK ON COMPOSITION OF 

CHEESE 



Per cent of fat 
in chee.se 


Per cent of 


Percentage of 


Ratio of fat 


proteins in 


cheese-solids in 


to proteins in 


cheese 


form of fat 


cheese 








Fat: Proteins 


(D— 35.1 


22.7 


55.7 


ir 0.65 


(2)— 33.3 


24.5 


53.0 


1- 0.74 


(3)— 31.1 


26.7 


49.4 


1: 0.86 


(4)— 25.2 


32.6 


40.0 


l: 1.30 


(S)— 16.1 


41.7 


25.5 


1: 2.60 


(6)— 2.3 


55.5 


3.7 


1: 24.00 



In making cheese from skim-milk, the yields 
given are lower than those obtained in commercial 



MILK AND COMPOSITION OF CHEESE 



235 



work, because here we allow for only 37 per cent 
of water, while commercial skim-milk cheese never 
contains so little moisture, but usually from 40 to 
55 per cent, the moisture held in cheese increasing 




FIG. 38 — DIAGRAM SHOWING EFFECT OF SKIMMING MILK 
UPON THE YIELD AND COMPOSITION OF CHEESE 

The figures immediately above each column give the number of pounds of 
cheese (containing 37 per cent of water) made from 100 pounds of milk. The figures 
within the diagram give the pounds of each constituent in cheese. The figures 
at the top of the diagram give the percentage of fat in milk and skim-milk. 

as the per cent of fat in skim-milk decreases. In com- 
paring the results in this table with those in the 
table on p. 2^)2, in which the composition is shown 
of cheese made from milk low and high in fat, 
we see that the difference there is the same in 



23O SCIENCE AND PRACTICE OF CHEESE- MAKING 

character as that brought about by partially skim- 
ming whole milk. For example, by skimming from 
100 pounds of Jersey milk, containing 5.78 per cent 
of fat, 1.25 pounds of fat, thus reducing the fat to 
4.53 per cent, the resulting milk and cheese will then 
be essentially the same in composition, in relation to 
cheese-solids, as the normal Holstein-Friesian milk, 
as shown by the following table : 



Holstein-Friesian milk 

Jersey milk (normal) 

Jersey milk (partially skimmed) 



Per cent 
of fat 



3.26 
5.78 
4.53 



Per cent 
of casein 



2.20 
3.03 
3.03 



Ratio of; fat 
to casein 



Fat : Casein 
1: 0.67 
1: 0.S2 
1: 0.67 



Of course, the same result could be accomplished 
by adding skim-milk to milk rich in fat. 

There is another way of comparing milks which, 
like these, are poor and rich in fat. Thus, how 
much fat would it be necessary to add to the Hol- 
stein-Friesian milk to have it make cheese like that 
made from Jersey milk? Calculation shows that 
nearly one pound of fat would need to be added 
to 100 pounds of the Holstein milk, which is thus 
shown : 



Fat in 


Fat added 


Per cent of fat 


Per cent of 


Ratio of fat 


milk 




in enriched milk 


casein in milk 


to casein 
Fat : Casein 


3.26 


4 0.94 


4.20 


2.20 


1: 0.52 



It can, therefore, be seen that the differences ex- 
isting between rich and poor milk are, so far as 
relates to the composition of the cheese made from 
them, such as can be adjusted by removing fat 



MILK AND COMPOSITION OF CHEESE 



^Z7 



from the rich milk or adding skim-milk to it, or by 
adding fat to skim-milk. The difference in milk 
poor in fat which makes the fat go farther in mak- 
ing cheese is a dift'erence which may be character- 
ized, in a general way, as a skim-milk difference, 
because it depends upon a relatively high proportion 
of casein. 

Composition of cheese made from milk contain- 
ing added cream. — Addition of cream to normal 
milk affects the cheese made from such milk in a 
way directly opposite to that produced by skim- 
ming; that is, it increases the proportion of fat in 
cheese in relation to proteins. A single illustration 
will suffice. We give the composition of cheese 
made from normal milk containing 4 per cent of fat 
and also from the same milk after its fat content has 
been increased to 6 per cent by the addition of 
cream. 



Per cent 

of fat 

in milk 



Pounds of 

cheese for 

100 pounds 

of milk 



Per cent 

of fat in 

cheese 



Per cent 
of pro- 
teins 
in cheese 



Per cent 

ofcheese- 

solids in 

form 

of fat 



Ratio of 

fat to 

proteins 



Normal milk. . 
Enriched milk 



4.00 
6.00 



10.60 
13.80 



35.1 
40.4 



22.7 
17.4 



55.7 
64.0 



Fat: 
Proteins 
1: 0.65 
1: 0.43 



THE UNITED STATES CHEESE STANDARD 



At this point it seems desirable to call attention 
to the standard of purity adopted for cheese by the 
United States Department of Agriculture in con- 
nection with the national pure-food law. Its defi- 
nition of cheese made from normal or whole-milk is as 



2^8 SCIENCE AND PRACTICE OF CHEESE-MAKING 

follows : "Standard whole-milk or full-cream cheese 
contains, in the water-free substance, not less than 
50 per cent butter-fat." There has been wide- 
spread and needless misunderstanding in regard to 
the meaning of this standard. Many have inter- 
preted it as meaning that normal or whole-milk 
cheese must contain 50 per cent of fat. The law 
does not say that at all, but that 50 per cent, not of 
the cheese, but of its zvatcr-frce substance (cheese- 
solids) must consist of butter- fat. This can easily 
be made clear by giving a specific illustration of 
its application, and, for this purpose, we take a ched- 
dar cheese of average composition, containing: 

Water 36.80 per cent. 

Water-free substance 63.20 ., 

Consisting of (100.00) 

Fat 33.75 

Proteins. . .23.75 
Salts, etc... 5.70 



63.20 



In order to apply the standard to any cheese, we 
need to know only the percentages of water and 
of fat. One then proceeds as follows : Subtract 
the percentage of water from lOO, which gives the 
cheese-solids or water-free substance, and then 
divide the percentage of fat in cheese by the per- 
centage of water-free substance. Expressed in out- 
line, the statement becomes: (i) lOO minus per cent 
of water=per cent of water-free substance; (2) per 
cent of fat-^per cent of water-free substance= 
per cent of fat in water-free substance. Example : 
(i) 100 — 36.80 (per cent of water in cheese) = 
63.20 (water-free substance in cheese). (2) 33.75 
(per cent of fat in cheese)-^63. 20=53.4, which is the 



MILK AND COMPOSITION OF CHEESE 239 

per cent of fat in the water-free substance of the 
cheese. In order that a cheese be below standard, 
the fat must be less than one-half of the water-free 
substance. In this particular case, the cheese would 
be belcw standard if the fat were less than 31.60 
per cent. 

The question naturally arises as to what actual 
basis there is for such a specific standard. It is 
based upon very extensive studies of cheese made 
from normal milk. The work of the New York ex- 
periment station with cheese made in New York 
factories has shown that the fat is always more 
than one-half of the total solids or water-free sub- 
stance of cheese. In the case of the lowest result, 
the percentage was 50.39 ; the highest, 56.83 ; and 
the average, 54. In very few cases was the per- 
centage of fat in cheese-solids found below 51.0. 
These results are in agreement with those obtained 
in other states. For example, in the Wisconsin 
cheese-scoring contests for April, May, June and July 
(1908), results are given, showing that, even in the 
cheese poorest in fat, the fat was 51.35 per cent of 
the water-free substance. The percentage of fat in 
the water-free substance of the cheese varied from this 
figure to 56.4 as the highest. 

In addition to the results of analysis of many 
samples of cheese made from normal milk, the 
composition of normal milk itself furnishes a good 
reason why the fat should amount to more than 
one-half of the water-free substance of cheese ; 
since a study of normal milk, as it is found at 
cheese-factories in New York state, shows that 
such milk does not contain enough casein, relative 



240 SCIENCE AND PRACTICE OF CHEESE-MAKING 

to fat, to make cheese of composition such that its 
water-free substance contains less than 50 per cent 
of fat, provided, of course, there is no abnormal 
loss of fat in the process of cheese-making. For 
example, it can readily be seen from the table on 
p. 234 that normal milk containing 4 per cent of 
fat can suffer a loss of nearly one-fourth of its fat, 
before the composition of the cheese drops below 
standard. Normal milk containing 3.50 per cent 
of fat can b'e reduced to about 3 per cent of fat 
before the cheese made from it contains less than 
50 per cent of fat in its water-free substance. 
Ordinary milk containiag 3 per cent of fat could 
have its fat reduced nearly to 2.75 per cent before 
making cheese below standard. These facts go to 
show that the United States standard is well above 
the limits of danger for cheese properly made from 
normal milk. 

Another question in connection with the cheese 
standard may be asked: Why not use as a standard 
the percentage of fat in the cheese itself in- 
stead of in the water- free substance? The present 
standard has for its purpose, the prevention of the 
use of skimmed milk for making cheese to' be sold as 
normal or whole-milk cheese. It does not aim to con- 
trol the amount of moisture in cheese. If the 
percentage of fat in cheese were used as a standard, 
then the amount of water in cheese would become 
an important factor ; because the greater the mois- 
ture content of cheese, the less the percentage of fat 
in the case of cheese made from milk of the same 
composition. It is recognized that different markets 
call for different percentages of water in cheese 



MILK AND COMPOSITION OF CHEESE 24I 

and, by basing the cheese standard on the water- 
free substance of the cheese, this condition has not 
been interfered with. 

Some of the state cheese standards. — In some 
states there are laws which aim to set up various 
standards according to the percentage of fat in 
cheese, having one percentage of fat for whole-milk 
cheese, another for partial-skim, another for half- 
skim and another for full-skim. Such provisions 
are cumbersome in legal administration, as well 
as demoralizing to the best interests of the cheese 
industry and deserve only severe condemnation. 

It is interesting to notice the legal provisions for 
cheese standards which are or have been in force 
in some states. In California full-cream (whole- 
milk) cheese must contain 30 per cent of fat; half- 
skim 15 per cent of fat; while full-skim cheese is 
any cheese made from skim-milk. Under these 
provisions it would be easily possible to make no 
normal-milk cheese, since all the cheese intended 
to comply with the requirements for so-called "full- 
cream" might be made from partially skimmed 
milk. In Colorado 35 per cent of the cheese-solids 
(water-free substances) must be fat. This is 15 
per cent below the United States standard. Under 
such a provision normal milk containing 4.0 per 
cent of fat could have one-half of its fat removed 
before the cheese would drop below the Colorado 
standard as given above. Under such circum- 
stances it would be a miracle if Colorado had an 
ounce of cheese made from normal milk except 
for the saving condition that the actual relation 
of such a standard is probably not clearly under- 
stood by Colorado cheese-makers and surely not 



242 SCIENCE AND PRACTICE OF CHEESE-MAKING 

by her legislators, it is to be hoped. In Minnesota, 
the law has required that 45 per cent of the 
cheese-solids be fat, which is too low. In Missouri, 
the only provision has seemed to be that the cheese 
should be made from milk containing not less than 
3 per cent of fat. In Ohio, cheese containing less 
than 20 per cent of fat is skim-cheese. This is 
certainly a very generous allowance, since cheese 
made from normal milk rarely contains less than 
;^2 per cent of fat even when green. It is to be 
hoped that the provisions in these states for whole- 
milk cheese have been or will be changed to 
conform with the provisions of the United States 
pure-food law. 

Misleading use of terms describing cheese. — The 
foregoing discussion impresses one with the unfor- 
tunate use of certain words in describing cheese 
made from normal milk or whole-milk. The ex- 
pressions, "full-cream/' ''factory-cream," etc., while 
in common commercial use, and clearly understood 
by those who use them, are misleading to one who 
interprets their meaning at their face value. Ap- 
parently, such terms imply normal milk contain- 
ing added cream. The use of the word cream in 
any form to describe normal milk is a relic of the 
inaccurate knowledge of former generations, and 
should be abandoned in the interests of clearness and 
precision. Whole-milk or normal milk is in every 
respect a much better expression to use in describing 
cheese made from milk that is normal. 



CHAPTER XX 

The Composition of Cheese in Relation 

to Quality 

In the preceding- chapter it has been demon- 
strated that cheese made from milk rich in fat 
contains relatively and actually more fat and less 
proteins than cheese made from milk poor in fat. 
Two such cheeses, made with equal skill, the milk 
being uniform in every way except in composition, 
show a marked difference in commercial quality 
(p. 244) ; and the one having the larger percentage 
of fat would be declared to be superior in quality. 
This has been demonstrated in practical ways by 
the experiment stations of Wisconsin, Iowa, Min- 
nesota and New York; and their work, the first to 
be done along these lines, has been supplemented 
and confirmed by the work of others. It has been 
found generally true that cheese made from milk 
containing added cream is superior in flavor and tex- 
ture to that made from ordinary normal milk; and 
that made from normal milk is superior in flavor, tex- 
ture, body and keeping quality to cheese made from 
skim-milk. 

Variation in quality in cheddar cheese follows 
more or less closely the relation of fat to proteins 
in cheese ; the larger the proportion of fat, the bet- 
ter, in general, the quality of cheese and the 
higher the market value. This fact is, of course, 
associated with, and dependent upon, the function 

243 



244 SCIENCE AND PRACTICE OF CHEESE-MAKING 

that milk-fat performs in cheese, that of imparting 
smoothness of feehng, mellowness of body, rich- 
ness and delicacy of ' taste and palatability. Bear- 
ing on this particular point, the late Henry E. 
Alvord makes the following statement (Yearbook 
of U. S. Dept. of Agr., 1895, P- 47i) • "Other things 
being equal, a cheese containing a large percentage 
of fat is better, because, first, of finer flavor and 
taste; second, of its better consistency; third, of its 
improved aroma ; fourth, of its increased digestibility ; 
fifth, of its more perfectly answering the requirements 
of a complete food or 'balanced ration.' " In this 
connection, it is interesting to learn that in Germany 
the custom of selling cheese according to the per- 
centage of fat contained in it is rapidly coming into 
use. 

While the view expressed above Is very generally 
held and is based upon experimental work, there 
have been no extensive commercial opportunities for 
demonstrating the matter in a systematic way. 
But some valuable facts bearing on this point in a 
most * direct and practical form have just been 
developed in the four Wisconsin cheese-scoring 
contests held during April, May, June and July, 
(1908). The facts are all the more Interesting be- 
cause they are merely incidental to the general pur- 
pose of these contests. The method of conducting 
these competitive tests In Wisconsin cannot be too 
highly recommended to other states, especially be- 
cause very full details are given, unusual under 
such circumstances, making the work of peculiar 
value in enabling one to study relations existing 



CHEESE COMPOSITION AND QUALITY 



245 



between the composition of cheese and its commer- 
cial value. In each of these monthly scorings, it h 
significant that the cheese scoring highest contained 
the largest amount of fat relative to proteins, while 
the cheese scoring lowest in every case contained the 
lowest amount of fat relative to proteins, as shov/n 
by the following data : 





Cheese scoring highest 


Cheese scoring lowest 




Per cent 
of fat 


Per cent 

of 
proteins 


Ratio of 

fat to 
proteins 


Per cent 
of fat 


Per cent 

of 
proteins 


Ratio of 

fat to 
proteins 


April 

May 

June 

July 


36. 
35.25 
35. 
35. 


27. 
27.4 
27.5 
29.46 


Fat:prot'ns 
1: 0.75 
1: 0.78 
1: 0.79 
1: 0.84 


32. 
35. 
34.5 
34.3 


29.2 
29.2 
29.8 
29.3 


Fat:prot'i s 
1: 0.91 
1: 0.83 
1: 0.86 
1: 0.86 



The most striking difference is shown by the 
April results, the least by those of July. In study- 
ing all the available data, the only apparent cause 
that accounts for these differences is the difference 
in composition. In the case of some of the cheeses 
that were scored second and third below the high- 
est, as compared with others that were scored second 
and third from the lowest, the general relation of 
quality and composition was shown but not equally 
in every case. While these results do not in them- 
selves absolutely prove the relation between composi- 
tion and commercial quality, their special value is that 
they confirm, in a different way, the results of other 
work. 

It cannot fail to be of value In the discussion of 
this subject to present the views of some of those 



246 SCIENCE AND PRACTICE OF CHEESE-MAKING 

who have been generahy regarded as authorities in 
relation to the commercial as well as to the scientific 
aspects of cheese-making. For this purpose, we 
have chosen to give the views ( i ) of Dr. Robert- 
son, so long Canada's most efficient leader in the 
progress of all branches of dairying and especially 
of cheese-making, and (2) of Dr. Babcock, who 
has been properly regarded as America's leading 
student of dairying in its scientific relations and 
who has given special attention to the question 
under discussion. 

In the Report of the New York Dairymen's 
Association for 1891, we find the following state- 
ments in an address given by Dr. Robertson : "In 
every case there was a gradual reduction in the 
quantity of cheese when there was a less quantity 
of butter-fat in milk. '. . . However, this is 
true also, that the increased yield of cheese is not 
in direct proportion to the increased percentage 
of butter-fat ; that is, milk containing 3 per cent 
of butter-fat will yield a certain quantity of cheese, 
but if you take milk having one-third more fat (4 
per cent) it will not yield one-third more cheese. 
At the same time, sucli milk is zvortJi one-third more 
for cheese-making, and thereby hangs a tale. You 
see, if it does not yield so much cheese, it makes a 
quality of cheese so much better that the market value 
of the cheese from 100 pounds of milk is a third 
greater than the market value of the cheese in the 
other case" (pp. 198-199). "Every two-tenths of a 
pound of butter-fat will improve the quality of the 
cheese one-eighth cent per pound, as near as I can 



CHEESE COMPOSITION AND QUALITY 247 

find out. Thus, you have a difference of about five- 
eighths of a cent per pound between cheese made 
from 3 per cent and 4 per cent milk" (p. 201). 

Dr. Babcock approaches the question from quite 
another point of view (Report of New York Dairy- 
men's Association for 1892, pp. 150, 153, etc.). 
After showing- that fat is the constituent controlHng 
the vahie of milk, cream and butter, he says : "It is 
evident that the market price of milk, of cream and of 
butter depends chiefly upon the price of butter-fat, 
and that other constituents have so little influence that 
they can practically be neglected. 

''There is one other important dairy product to be 
considered, and that is cheese. Does the same prin- 
ciple hold with this? I believe it does, for on no 
other basis can I reconcile market prices all over the 
world." 

He then goes on to show by actual market quo- 
tations that cheese varies in price according to 
its richness in fat, all the way from 11 cents per 
pound for whole-milk, fancy cheese down to i to 
2^ cents a pound for full-skim cheese. Antici- 
pating some objections raised to the method of 
reasoning as applied to the fat basis as a method 
of paying for milk at cheese-factories, he con- 
tinues : 'T cannot leave this subject without refer- 
ring to some of the objections made to its use in 
cheese-factories. It is urged that because casein 
and fat are intimatelv mixed tos^ether in cheese, 
they bring the same price per pound when sold, 
and so should be given the same price in calculat- 
ing the value of milk that is to be used for this pur- 
pose. If this is true, the water which comprises a 



248 SCIENCE AND PRACTICE OF CHEESE-MAKING 

larger proportion of cheese than the casein should 
be treated in the same way, and worthless constit- 
uents in any product should have the same value 
as the mixture in which they occur. It is absurd, 
on the face of it, as it gives entirely different values, 
to the same constituent according to the product 
considered. It makes the casein, water and fat 
worth each about one cent per pound in milk, the 
same constituent worth 30 cents per pound in but- 
ter and anywhere from i to 11 cents per pound in 
cheese, according to the proportions in which they 
are mixed. Whereas, the relative value plan gives 
consistent values in all. 

"Again, it is said that the life-sustaining power 
of a pound of casein is about the same as a pound 
of fat, and that they should therefore have about 
the same value ; but it must be borne in mind that 
the nutritive value and the market value of foods have 
no relation to each other. You can buy nutrients 
in corn meal cheaper than you can in wheat flour. 
Maple sugar costs you two or three times as much 
as beet sugar, although the two have identically 
the same effect. All of these things are con- 
trolled by the universal law of supply and demand, 
and have nothing to do with their relative food 
value. 

"When any article has a high value for any 
special purpose, that fixes the price which must 
be paid for it for all other purposes. You cannot 
afford the use of rosewood or mahogany for fuel, 
not because they have less heat-producing power 
than maple or birch, but because they command a 
higher price for piano cases or other articles of 



CHEESE COMPOSITION AND QUALITY 249 

furniture. The general public esteems butter-fat more 
highly than casein and are willing to pay a much 
higher price for it. It is folly to stand in your own 
light and argue that this is inconsistent." 

These arguments of Dr. Babcock are based on 
general economic truths which hold good to-day as 
fully as when they were stated by him. They are 
facts which should be kept in mind when considering 
the relation of composition of cheese to commercial 
quality or market value. In the 1 2th annual report 
of the Wisconsin experiment station (p. 115), Dr. 
Babcock also says : 

"It is a well-established fact that rich milk gives 
a better quality of cheese, which commands a higher 
price, than that from poor milk." 

We add also the following quotation from an 
address given before the Wisconsin cheese-makers' 
convention at Milwaukee, in 1907, by Prof. E. H. 
Farrington, dairy husbandman at the Wisconsin ex- 
periment station : 'Tt will be seen that the richer the 
milk, the better the price per pound of cheese 
made from it. I am occasionally asked if 100 
pounds of milk testing 6 per cent of fat will make 
twice as much cheese as 100 pounds of milk test- 
ing 3 per cent of fat. The answer to this question 
is briefly that the cheese made from the richer 
milk is of much better quality and worth a higher 
price per pound than that made from the thinner 
milk, and this will help balance any difference in 
yield. The influence of the richness of milk on 
the quality of cheese is something that should 
not be lost sight of in considering the question of 



250 SCIENCE AND PRACTICE OF CHEESE-MAKING 

paying for milk at a cheese-factory by the Babcock 
test." 

SKIM-MILK CHEESE 

The manufacture of skim-milk cheese has been 
fostered and protected in some of our states. There 
are some considerations worthy of our attention in 
connection with the discussion of the composition of 
cheese in relation to quality. 

(i) The removal of fat from ordinary normal 
milk, such as the mixed milk of our cheese-fac- 
tories, results in producing cheese that differs in 
composition from whole-milk cheese. Such cheese, 
as we have seen, contains less fat and more casein 
than that made from normal milk having the same 
percentage of fat. Skim-milk cheese is an adul- 
terated food product, according to the legal defini- 
tion of adulteration. 

(2) It is impossible to remove fat from ordi- 
nary normal milk without affecting the composi- 
tion of the cheese unfavorably, and along with 
this, the quality as well. While skim-milk cheeses 
may differ from one another in composition and 
quality, they are all inferior to whole-milk cheese 
properly made from normal milk of good quality in 
all respects. 

(3) Skim-milk cheese is not only deficient in 
fat, but it always contains an abnormally high 
percentage of water. This is absolutely necessary 
in order to make it edible and have it appear in 
body and general quality as a good imitation of 
whole-milk cheese. A skim-milk cheese containing 



CHEESE COMPOSITION AND QUALITY 25 1 

only the amount of water held by a whole-milk cheese 
would be practically unsalable on account of its 
hardness and toughness. High percentages (50-55) 
of water are necessary in order to make the cheese 
appear to contain fat and have a smooth-feeling 
body. 

(4) Skim-milk cheese, on account of its high per- 
centage of water, dries out very rapidly under ordinary 
conditions in the hands of the consumer and becomes 
inedible, though it can then be used by experts in some 
forms of cooking. 

(5) Skim-milk cheese, on account of its high per- 
centage of water and of proteins, does not possess 
the keeping qualities of whole-milk cheese. It 
develops undesirable flavors more easily and does not 
have the same length of life under the same condi- 
tions, especially when kept at temperatures above 
60° F. 

(6) Skim-milk cheese generally becomes digestible 
less readily than whole-milk cheese kept under the 
same conditions ; and when its proteins become rapidly 
soluble, offensive flavors usually develop, destroying 
its value. 

(7) The retail price of skim-milk cheese is always 
too high in comparison with whole-milk cheese. 
Separator skim-milk cheese usually sells at retail for 
10 cents a pound, when whole-milk cheese sells for 16 
cents. Such skim-milk cheese sells for more than 
three times its real value. 

(8) The consumer is not really protected, even 
when an attempt is made by the state to do so. 
How many people want or even ask for skim- milk 
cheese? The average consumer is ignorant of 



252 SCIENCE AND PRACTICE OF CHEESE-MAKING 

systems of branding or other methods devised for his 
protection. He simply asks for cheese and takes 
what is offered. It should be made as dangerous 
for retailers to sell skim-milk cheese for whole- 
milk cheese as it is for them to sell chicory for pure 
coffee. 

(9) The indiscriminate sale of skim-milk cheese 
inevitably injures the sale of whole-milk cheese. 

(10) Skim-milk, consumed as such or in the 
form of cottage-cheese, is a more economical and 
nutritious food than when used as skim-milk 
cheese. 

(11) There is a strong inclination on the part 
of those interested in the cheese industry to believe 
that the real interests of dairymen and of the general 
public would be best protected and promoted by the 
absolute prohibition of skim-milk cheese, as demon- 
strated bv Canada. 



CHAPTER XXI 

Methods of Paying for Milk for 
Cheese-Making 

The subject relating to methods of paying for 
milk at cheese-factories has been one of more or 
less constant discussion for about twenty years. 
Shortly before the year 1890, some question was 
raised as to the fairness of paying for milk at 
cheese-factories by weight. Two factors worked 
against the realization of any practical results 
coming from such discussion : ( i ) Lack of knowl- 
edge regarding the relation of milk-constituents to 
yield and quality of cheese, and (2) the need of 
a practicable method for determining any of the 
cheese-making constituents of milk. In 1890 Dr. 
Babcock furnished his method of determining fat 
in milk, and then the discussion soon centered 
about the use of fat in milk as a basis for paying 
for milk used in cheese-making. The application 
of the test in the case of butter-making was at 
once understood and utilized ; but, in connection 
with cheese-making, it was known that two con- 
stituents are concerned, fat and casein, and the 
question was therefore more complicated than in 
the case of butter-making, where only fat was con- 
cerned. During the years 1891 to 1895, a large 
amount of investigation was carried on, which re- 
sulted in giving us such a comprehensive and sys- 

253 



254 SCIENCE AND PRACTICE OF CHEESE-MAKING 

tematic knowledge of the relations of milk constitu- 
ents to cheese as had not been possible previously. 
In general, it was shown that, while the amount of 
fat in milk is not an absolute guide in respect to 
the yield of cheese from milks containing differ- 
ent amounts of fat, it is a very much more accurate 
index than the mere weight of milk; and that, 
while, in case of milks containing higher percent- 
ages of fat, the yield of cheese is usually less for 
a pound of milk-fat than in the case of milk con- 
taining lower percentages of fat (p. 207), the cheese 
made from the richer milk is of more excellent 
quality and has a higher commercial value (pp. 

243-249). 

The fat basis began to be introduced into actual 
cheese-factory work about 1892, and its use spread 
quite rapidly during the next few years. This 
method was at first received with considerable- en- 
thusiasm. After a few years a reaction gradually 
took place and the system was abandoned in many 
factories, which went back to the old method of pay- 
ing for milk by weight only. There are several reasons 
why the fat basis in paying for milk for cheese-mak- 
ing has experienced its ups and downs, like every 
other reform movement, and we will notice some of 
the most prominent of these. 

(i) Wherever the fat basis replaced the weight- 
of-milk method, the change affected the dividends of 
different patrons in different ways. Those furnish- 
ing milk containing percentages of fat above the 
average received more money for their milk, while 
those furnishing milk containing percentages of 



PAYING FOR MILK FOR CHEESE-MAKING 255 

fat under the average found their dividends re- 
duced. Therefore, the owners of cows giving milk 
low in fat were bitterly disappointed and exercised 
their ingenuity in discovering reasons why the fat 
basis was objectionable and unfair. This attitude 
of the producer of poor milk is, of course, the 
fundamental reason why the fat basis has been 
abandoned in some cases where it had been intro- 
duced. The other objections raised were subordinate 
to this one, though some of them had, perhaps, some 
real basis. 

(2) The reliability of the Babcock test was 
attacked and the accuracy of its results called into 
question. The points of objection raised on this 
ground were, (a) that the Babcock method of 
testing milk for fat is unreliable under all circum- 
stances ; (b) that, while the method, when properly 
handled, is accurate, cheese-makers are careless 
or inefficient in operating the test, and their results 
are therefore inaccurate; (c) that the glassware 
was not always accurately graduated and conse- 
quently gave incorrect results; (d) that cheese- 
makers deliberately gave some patrons higher 
results than those indicated by the test. The gen- 
eral charge of inaccuracy of the test itself was, 
of course, prompted by ignorance or malice or both. 
There was probably once some justification for the 
charge of carelessness and inefficiency against 
operators of the Babcock test ; for it was un- 
doubtedly true to some extent that cheese-makers 
attempted to employ the method who had not been 
properly instructed in its use nor acquired the 
requisite accuracy of manipulation. There was at 



256 SCIENCE AND PRACTICE OF CHEESE-MAKING 

one time a strong disposition to over-emphasize 
the extreme simphcity of the Babco.ck test and to 
lose sight of the fact that even so simple a method 
requires careful attention to every detail and that 
certain precautions must be strictly observed. It 
was also true that some manufacturers became care- 
less and put on the market glassware that was inac- 
curate. This difficulty has been effectively overcome 
in most of the prominent dairy states by an official 
testing of all graduated glassware used in the Babcock 
test, before it is placed on sale. 

(3) Many cheese-makers object to the added work 
involved, even when paid for it. An unwilling 
cheese-maker can easily influence patrons against the 
method. 

(4) Another cause for the discarding of the fat 
basis in many cases was the confusion introduced 
by proposing some modification of the method in the 
interest of the producer of poorer milk, a point which 
we will consider more fully later. 

In the history of the cheese-making industry, we 
can distinguish in the order of their appearance, five 
methods which have been proposed for the purpose 
of paying for milk at cheese-factories : 

(i) Weight of mill 

(2) Amount of fat in milk. 

(3) Relative values of fat and other cheese-solids 
based on yield and composition of cheese. 

(4) Modification of fat basis to include part of the 
milk-casein. 

(5) Amount of fat and casein in milk. 

We will now consider each of these methods as to 
their comparative merits and defects. 



PAYING FOR MILK FOR CHEESE-MAKING 257 

PAYING FOR MILK ON BASIS OF WEIGHT 

Under this system each patron receives the same 
amount of money for eacli lOO pounds of milk de- 
livered at the factory. This method possesses the 
advantage of simplicity and economy of time, in- 
volving no additional work. Among the disadvan- 
tages of this method are the following : ( i ) It 
assumes, as a fundamental basis of its fairness, 
that all kinds of normal milk have the same cheese- 
producing value; that, from lOO pounds of any 
milk, we make the same amount of cheese. This 
assumption has been abundantly proved not to be 
true, since the yield of cheese from loo pounds of 
milk may (p. 207) vary all the way from 8 to 13 
pounds or more. The method is, therefore, unfair 
to the producers of milk containing higher per- 
centages of fat. (2) This system discourages the 
production of milk of higher percentage in fat. 
When weight alone is considered in making pay- 
ment, more money can be received by increasing 
the amount of milk produced, without regard to 
its composition ; and it is thus found more profit- 
able to produce milk as low in fat as legal require- 
ments permit. (3) This system breeds criminality, 
because it encourages the addition of water, re- 
moval of cream and all similar forms of dishonesty. 
Some dairymen have regarded the direct addition 
of water to milk as the most economical way of 
increasing milk production for cheese-making pur- 
poses, but the experience is not usually attended 
with most economical results for any length of 
time. 



258 SCIENCE AND PRACTICE OF CHEESE-MAKING 

However much difference of opinion there may 
exist in regard to the efficiency of different methods 
of paying for milk for cheese-making, all who are 
in position to give a reliable judgment in the matter 
agree on this one point, viz., among the various 
methods proposed, this one is farthest from doing 
justice to all producers of milk. 

PAYING FOR MILK ON BASIS OF FAT 

When milk is paid for on the basis of its fat 
content, each patron receives a certain amount of 
money for each pound of fat in the milk delivered. 
The patron whose milk contains 3 per cent of fat 
receives payment for 3 pounds of fat for each 100 
pounds of milk delivered by him ; while the patron 
whose milk contains 4 per cent of fat receives pay- 
ment for 4 pounds of fat for each 100 pounds of milk 
furnished by him. The second patron receives one- 
third more per 100 pounds of milk than the first one, 
while, under the weight-of-milk method, each would 
receive an equal sum. This can be illustrated as 
follows : 

For the sake of simplicity, we will compare the 
milks furnished by two patrons, one milk con- 
taining 3, and the other 4, per cent of fat. We 
will assume that the cheese sells for 10 cents a 
pound. We will make the comparison on the basis 
of 100 pounds of milk, allowing that the cheese 
yield from 100 pounds of milk containing 3 per 
cent of fat is 8.30 pounds, and from milk contain- 
ing 4 per cent of fat, 10.60 pounds, a total of 18.90 
pounds, bringing 189 cents. By the weight-of-milk 
method, this sum is divided equally between the 



PAYING FOR MILK FOR CHEESE-MAKING 



259 



two patrons, because each furnishes the same 
amount of milk. Hence, each receives 94.5 cents 
for the cheese made from his milk. On this basis 
the one furnishing milk containing 3 per cent of 
fat receives 11. 4 cents a pound for each pound of 
cheese made from milk furnished by him ; while the 
other receives 8.9 cents for each pound of cheese made 
from his milk. 

Dividends based on the percentage of fat in milk 
are n?ade as follows : One patron furnishes 3 
pounds of fat and the other 4. There are, all 
told, 7 pounds of fat, the cheese corresponding to 
which sells for 189 cents. Therefore, each pound 
of fat is credited with 2y cents ; one patron re- 
ceives 81 {'^yy,'^) cents and the other, 108 (27X4) 
cents. In this case the one furnishing the poorer 
milk receives 9.76 cents a pound for the cheese 
made from his milk, and the other, 10.19 cents. The 
existing difference, 0.4 cents a pound, is generally- 
held to represent an actual difference in the quality 
and value of the cheese (p. 242). These results 
can be very well shown in the following tabulated 
form : 







Weight-ot-Miik Method 


Milk-Fat Basis 


Pounds 
of fat 
in 100 
pounds 
of milk 


Pounds 
of cheese 

made 

from 100 

pounds 

of milk 


Divi- 
dend 


Money 

rec'd for 

each 

pound 

of 
cheese 


Money 
rec'd for 
each 
pound 
of milk- 
fat 


Divi- 
dend 


Money 

rec'd for 

each 

pound 

of cheese 


Money 
rec'd for 
each 
pound 
of milk- 
fat 


3 

4 


8.30 
10.60 


Cents 

94.5 

94.5 


Cents 

11.4 

8.9 


31.5 
23.6 


Cents 

81 

108 


Cents 

9.76 

10.19 


Cent? 
27 
27 



2(J0 SCIENCE AND PRACTICE OF CHEESE-MAKING 

Of the various objections deserving any atten- 
tion which have not been already noticed, the fol- 
lowing are the chief ones urged against this 
method : 

(i) The percentage of fat in milk is not gen- 
erally an accurate measure of the amount of cheese 
made from lOO pounds of milk. A pound of fat in 
milk containing 3 per cent of fat represents more 
cheese than does a pound of fat in milk containing 
4 per cent of fat; in the former case, the cheese yield 
is 2.'/y pounds for one pound of fat in milk, while in 
the latter it is 2.65 pounds. On this account, the milk 
containing least fat does not receive pay for all the 
cheese it makes. 

(2) The cost of making the test is often raised as 
an objection. In actual practice, the difficulty has 
been satisfactorily overcome. The usual custom is 
to pay the cheese-maker at the rate of 20 to 25 cents 
a month for each patron. 

The principal reasons given for favoring the fat 
basis are the following: 

( 1 ) This method recognizes the fundamental truth 
that normal milks varying in percentage of fat possess 
different values for cheese-making. 

(2) The amount of fat in milk offers a practicable 
and just basis for determining the cheese-producing 
value of milk, when we consider both quality and 
quantity (p. 242). 

(3) All temptation to adulterate milk by water- 
ing or skimming is absolutely removed, since a 
man receives pay for the number of pounds of fat 
that he furnishes and not merely for the number of 
pounds of liquid he carries to the factory. No other 



PAYING FOR MILK FOR CHEESE-MAKING 26l 

method now in use so completely eliminates the 
temptation to adulterate milk. 

(4) This method promotes improvement in the 
character of milk production. This is not merely a 
theoretical statement, but has been proved to be true 
in practice. It offers an inducement to each dairyman 
to improve the composition of his milk. 

(5) Improvement in the character of dairy animals 
and in the consequent yield and composition of milk 
means economy of production and increase of profit. 
Cheese-solids in rich milk can be produced at less cost 
than in poor milk. 

(6) This method awakens interest in the subject 
of milk production, stimulates a desire for further 
knowledge and tends to place the production of milk 
on a higher plane of intelligence. 

PAYING FOR MILK ON THE BASIS OF 

YIELD AND RELATIVE VALUE OF 

CHEESE-SOLIDS 

In the twelfth annual report of the Wisconsin 
experiment station (pp. 114-119), Dr. Babcock has 
worked out a system of payment by which the 
yield of cheese and composition are both taken 
into consideration. The principles embodied in 
this method have not received the general attention 
deserved. "It is not sufficient for a system to give 
the true yield from each patron's milk, for this 
makes skim-milk cheese equally valuable with that 
from the richest milk. The perfect system of 
making dividends In cheese-factories must include, 
not only the amount, but also the relative values 



262 SCIENCE AND PRACTICE OF CHEESE-MAKING 

of fat and the other cheese-producing soHds ; with 
such a system each patron will receive his just pro- 
portion whether he brings skim-milk, watered milk 
or cream." His proposed method gives to milk- 
fat a value of 6.6, as compared with a value of i.o 
for the cheese-solids not fat. The following table 



Per 








Lactometer Degrees 








Per 


cent 






















cent 


of 
























of 


fat 


26 


27 


28 


29 


30 


31 


32 


ZZ 


34 


35 


36 


fat 


2.0 


2.86 


2.88 


2.89 


2.91 


2.93 


2.94 


2.96 


2.98 


3.00 


3.01 


3.03 


2.0 


2 1 


2.98 


3.00 


3.01 


3.03 


3.05 


3.06 


3.08 


3.10 


3.12 


3.13 


3.15 


2.1 


2.2 


3.10 


3.12 


3.13 


3.15 


3.17 


3.18 


3.20 


3.22 


3.24 


3.25 


3.27 


2.2 


2,3 


a ' ^ 


3.24 


3.25 


3.27 


3.29 


3.30 


3.32 


3.34 


3.36 


3.37 


3.39 


2.3 


2.4 


J. 34 


3.36 


3.37 


3.39 


3.41 


3.42 


3.44 


3.46 


3.48 


3.49 


3.51 


2.4 


2.i 


3.47 


3.49 


3.50 


3.52 


3.53 


3.54 


3.5,6 


3.58 


3.60 


3.61 


3.63 


2.5 


2.6 


3.59 


3.61 


3.62 


3.64 


3.65 


3.67 


3.69 


3.71 


3.73 


3.74 


3.76 


2.6 


2.7 


3.71 


3.73 


3.74 


3.76 


3.77 


3.79 


3.81 


3.83 


3.85 


3.86 


3.88 


2.7 


2.8 


3.83 


3.85 


3.86 


3.88 


3.90 


3.91 


3.93 


3.95 


3.97 


3.98 


4.00 


2.8 


2.9 


3.95 


3.97 


3.98 


4.00 


4.02 


4.03 


4.05 


4.07 


4.09 


4.10 


4.12 


2.9 


3.0 


4.07 


4.09 


4.10 


4.12 


4.14 


4.15 


4.17 


4.19 


4.21 


4.22 


4.24 


3.0 


5.1 


4.19 


4.21 


4.22 


4.24 


4.26 


4.27 


4.29 


4.31 


4.33 


4.34 


4.36 


3.1 


3.2 


4.31 


4.33 


4.34 


4.36 


4.38 


4.39 


4.41 


4.43 


4.45 


4.46 


4.48 


3.2 


3.3 


4.43 


4.45 


4.46 


4.48 


4.50 


4.51 


4.53 


4.55 


4.57 


4.58 


4.60 


Z.Z 


3.4 


4.55 


4.57 


4.58 


4.60 


4.62 


4.63 


4.65 


4.67 


4.69 


4.71 


4.72 


3.4 


3.5 


4.68 


4.70 


4.71 


4.73 


4.75 


4.76 


4.78 


4.80 


4.82 


4.83 


4.85 


3.5 


3.6 


4.80 


4.82 


4.83 


4.85 


4.87 


4.88 


4.90 


4.92 


4.94 


4.95 


4.97 


3.6 


3.7 


4.92 


4.94 


4.95 


4.97 


4.99 


5.00 


5.02 


5.04 


5.06 


5.07 


5.09 


3.7 


3.8 


5.04 


5.06 


5.07 


5.09 


5.11 


5.12 


5.14 


5.16 


5.18 


5.19 


5.21 


3.8 


3.9 


5.16 


5.18 


5.19 


5.21 


5.23 


5.24 


5.26 


5.28 


5.30 


5.31 


5.33 


3.9 


4.0 


5.29 


5.31 


5.32 


5.34 


5.36 


5.37 


5.39 


5.41 


5.43 


5.44 


5.46 


4.0 


4.1 


5.41 


5.43 


5.44 


5.46 


5.48 


5.49 


5.51 


5.53 


5.55 


5.56 


5.58 


4.1 


4.2 


5.53 


5.55 


5.56 


5.58 


5.60 


5.61 


5.63 


5.65 


5.67 


5.68 


5.70 


4.2 


4.3 


5.65 


5.67 


5.68 


5.70 


5.72 


5.73 


5.75 


5.77 


5.79 


5.80 


5.82 


4.3 


4.4 


5.77 


5.79 


5.80 


5.82 


5.84 


5.85 


5.87 


5.89 


5.91 


5.92 


5.94 


4.4 


4.5 


5.89 


5.91 


5.92 


5.94 


5.96 


5.97 


5.99 


6.01 


6.03 


6.04 


6.06 


4.5 


4.6 


6.02 


6.04 


6.0s 


6.07 


6.09 


6.10 


6.12 


6.14 


6.16 


6.17 


6.19 


4.6 


4.7 


6.14 


6.16 


6.17 


6.19 


6.21 


6.22 


6.24 


6.26 


6.28 


6.29 


6.31 


4.7 


4.8 


6.26 


6.28 


6.29 


6.31 


6.33 


6.34 


6.36 


6.38 


6.40 


6.41 


6.43 


4.8 


4.9 


6.38 


6.40 


6.41 


6.43 


6.45 


6.46 


6.48 


6.50 


6.52 


6.53 


6.55 


49 


5.0 


6.50 


6.52 


6.53 


6.55 


6.57 


6.58 


6.60 


6.62 


6.64 


6.65 


6.67 


5.0 


5. J 


6.62 


6.64 


6.65 


6.67 


6.69 


6.70 


6.72 


6.74 


6.76 


6.77 


6.79 


5.1 


5.2 


6.74 


6.76 


6.77 


6.79 


6.81 


6.82 


6.84 


6.86 


6.88 


6.89 


6.91 


5.2 


5.3 


6.86 


6.88 


6.89 


6.91 


6.93 


6.94 


6.96 


6.98 


7.00 


7.01 


7.03 


5.3 


5.4 


6.98 


7.00 


7.01 


7.03 


7.05 


7.06 


7.08 


7.10 


7.12 


7.13 


7.15 


5.4 


5.5 


7.10 


7.12 


7.13 


7.15 


7.17 


7.18 


7.?0 


7.22 


7.24 


7.25 


7.27 


5.5 


5.6 


7.23 


7.25 


7.26 


7.28 


7.30 


7.31 


7.33 


7.35 


7.37 


7.38 


7.40 


5.6 


5.7 


7.35 


7.37 


7.38 


7.40 


7.42 


7.43 


7.45 


7.47 


7.49 


7.50 


7.52 


5.7 


5.8 


7.47 


7.49 


7.50 


7.52 


7.54 


7.55 


7.57 


7.59 


7.61 


7.62 


7.64 


5.8 


5.9 


7.59 


7.61 


7.62 


7.64 


7.66 


7.67 


7.69 


7.71 


7.73 


7.74 


7.76 


5.9 


6.0 


7.71 


7.73 


7.74 


7.76 


7.78 


7.79 


7.81 


7.83 


7.85 


7.86 


7.88 


6.0 



PAYING FOR MILK FOR CHEESE-MAKING 263 

is worked out, based on yield of cheese and relative 
value of cheese-solids for milks containing different 
percentages of fat from 2 to 6. Values are given 
which can be used directly in the same manner 
as the percentages of fat are used in the fat basis. 
These values appear to be quite accurate, especially 
for milks containing 3.5 to 4.0 per cent of fat. 
The only additional labor required is to apply the 
lactometer to a sample of each milk and take the 
reading. ''This modification would give to each 
patron the same amount of money which he would 
obtain if his milk were manufactured by itself. In 
this respect it differs widely from those modifica- 
tions of the relative'-value plan which aim to make 
dividends in proportio-n to the pounds of cheese 
which each milk will produce, leaving out entirely 
the quality of the cheese." Tlie following illustration 
shows the application of this method: 

One patron furnishes milk showi-ng by test 3 
per cent of fat and a lactometer (Quevenne) read- 
ing of 28; another, milk with 4 per cent of fat and 
a lactometer reading of 34. Turning t>o the preced- 
ing table, it is found that milks corresponding to 
these percentages of fat and lactometer readings 
have relative values for cheese-making represented 
by the -numbers 4.10 and 5.43. To find the dividend 
of each we divide the amount of money (189 cents) 
corresponding to tlie sum (9.53) of these two num- 
bers, which gives 19.83. This number multiplied by 
4.10 and 5.43 gives the respective dividends of the 
two patrons. 



264 SCIENCE AND PRACTICE OF CIIEESE-MAKING 



Pounds of 

fat in 

100 pounds 

of milk 


Pounds of 

cheese made 

from 100 

pounds of milk 


Dividend 


Money rec'd 

for each 

pound of 

cheese 


Money rec'd 
for each 
pound of 
milk-fat 


3 

4 


8.30 
10.60 


Cents 

81.3 

107.7 


9.80 
10.16 


Cents 
27.10 
26.92 



By comparing these results with those given by the 
simple fat basis (p. 259), and other methods, we see 
that the values are much closer to the results of the 
fat basis than by any other method. 

Application of principle to fat and casein. — This 
same principle could be readily applied when we 
know the percentages of fat and of casein in milk. 
We might be even more liberal and, instead of al- 
lowing only one-sixth for casein, allow as much 
as one-fourth. In this case, the dividends would 
be based on the fat plus one-fourth of the casein 
in each case. This is illustrated in connection with 
the fat and casein method of making dividends (p. 
270). 

MODIFICATION OF FAT BASIS KNOWN AS 
THE "FAT-PLUS-TWO" METHOD 



By this method the percentage of fat in milk is 
increased by 2 and the result used as in making 
dividends on the fat basis. The method originated 
in Canada. The first suggestion was made about 
1893, when at one of the cheese-factories the plan 
was adopted of adding i to the fat in making divi- 
dends, because it was noticed that this method 
more closely approximated the cheese yield than 



PAYING FOR MILK FOR CHEESE-MAKING 



265 



the use of fat alone. This method was made a sub- 
ject of study at the Ontario Agricultural College and 
was modified by adding 2 to the fat in making 
dividends. 

The dividends are made in the following manner 
under this method, using the illustration already 
given (p. 258) for milks containing 3 and 4 per cent 
of fat. The receipts from sale of cheese are 189 cents. 
Instead of one patron receiving three-sevenths and the 
other four-sevenths of this amount, one receives 
five-elevenths and the other six-elevenths, as shown 
thus; 

3+2=5 
4+2=6 



II 



The results, compared with those of the fat basis, 
are as follows for this particular illustration : 





Pounds 
of cheese 

made 

from 100 

pounds 

of milk 


Fat-Basis method 


Fat-plus-2 method 


Pounds 
of fat 
in 100 
pounds 
of milk 


Divi- 
dend 


Money 
received 
for each 

pound 
of 

cheese 


Money 
received 
for each 

pound 

of 

milk-fat 


Divi- 
dend 


Money 
received 
for each 

pound 
of 

cheese 


Money 
received 
for each 

pound 

of 
milk-fat 


3 
4 


8.30 
10.60 


Cents 

81 

108 


Cents 

9.76 

10.19 


27 
27 


86 
103 


Cents 
10.36 
9.72 


Cents 
28.7 
25.7 



This method is based on an attempt to approxi- 
mate yield of cheese as a basis to use in paying 
for milk. It is supposed that the addition of 2 to 



266 SCIENCE AND PRACTICE OF CHEESE-MAKING 

the per cent of fat makes allowance for the casein 
of the milk, and, therefore, that milks which are 
low in fat will get such a proportion of casein as 
will balance the difference existing between milk 
poor in fat and milk rich in fat in respect to yield 
of cheese per pound of fat; and that, therefore, 
taking the casein into consideration along with the 
fat will give us a more accurate relation in regard 
to yield of cheese and percentage of fat in milk. 
This ought to be true and is true to a certain degree. 
So far as we do take casein into consideration, we 
get just that much nearer to the average of cheese 
yield, speaking of yield alone and not considering 
quality. 

The objections which have been brought against this 
method are the following: 

(i) It does not recognize any casein in milk 
above 2 per cent ; it would be a fair measure of 
yield of cheese if all milks contained 2 per cent of 
casein, no more and no less. This is, of course, 
not in accordance with the actual facts. The addi- 
tional amount of casein above 2 per cent, which is 
usually found in richer milks, is wholly ignored by 
this method. For example, under this method, milk 
containing 4 per cent of fat would, after adding 2, 
be given a value of 6, whereas it should be given a 
value of 6.4 or 6.5 or more on the basis of its usual 
casein content. 

(2) This method is, therefore, in the interest of 
milk low in fat. It gives undue advantage to 
poorer milk, and, to the same extent, works against 
the producer of richer milk. It has been generally 
held that too much encouragement cannot be given 



PAYING FOR MILK FOR CHEESE-MAKING 267 

to farmers to produce milk of richer composition. 
In the illustration given above, one fails to see the 
justice of a method which gives to the producer of 
poorer milk 10.36 cents a pound for his cheese and 
to the producer of richer milk, only 9.72 cents a 
pound for cheese that is better if the milk is made 
up by itself. 

(3) This method offers a premium on watering 
milk, because the percentage of fat in milk (high 
or low) is credited with only 2 per cent of casein; 
and, hence, the lower the percentage of fat, the 
larger will be the relative amount of casein and 
the greater the price received for each pound of fat. 
For example, a patron furnishing milk with 4 per 
cent of fat could add, say, ^;^ pounds of water to 
100 pounds of milk, thus reducing the percentage 
of fat to 3. He would then have the benefit of 
the added factor for 133 pounds of milk instead of 
100 pounds. He would thereby increase his dividend 
from 103 to 108 cents. 

(4) This method also offers a premium on 
skimming as well as watering milk. This can best 
be made clear by illustration. A patron who 
furnishes milk containing 4 per cent of fat skims 
it so as to make it contain 3 per cent and then 
adds enough water to make the weight of milk 
100 pounds again. The cheese made from 100 
pounds of such milk would be about 8.9 pounds. 
The milk of the other patron, who furnishes 100 
pounds of normal milk containing 3 pounds of fat, 
makes 8.3 pounds of cheese, a total of 17.2 pounds 
for the 200 pounds of mixed milk. ■ This, we assume, 
sells for 172 cents and is evenly divided between 



268 SCIENCE AND PRACTICE OF CHEESE-MAKING 

the two patrons, because each furnishes milk con- 
taining 3 per cent of fat. Each, therefore, receives 
86 cents. If the patron who produces milk with 4 
per cent of fat takes the normal milk to the factory, 
he receives on the "fat-plus-two" basis 103 cents, as 
we have already seen. If he skims his milk as de- 
scribed above, he receives 86 cents, or 17 cents less; 
but he has, as an offset to this, one pound of milk-fat 
which he can sell for 25 cents to 30 cents. There- 
fore, he is the gainer by all that he can get for his 
pound of milk-fat over 17 cents. 

(5) This method, in opposition to the teachings of 
Robertson, Babcock and many others, wholly ignores 
the fact that composition and quality vary with fat 
in milk and that cheese made from richer milk is of 
higher value. 

While these objections hold good, still the ''fat- 
plus-two" method is unquestionably a great ad- 
vance over the old weight-of-milk method. The 
most unfortunate feature about this method is the 
confusion which its introduction has caused among 
dairymen. Instead of regarding it as a modifica- 
tion of the fat basis, dairymen have, in many cases, 
thought that the whole principle of paying for milk 
by any other method than the weight-of-milk 
system was under suspicion. Dairymen do not 
yet understand the details of different methods 
clearly enough to discriminate, and, when they 
are told that the fat basis is unreliable and in- 
accurate, they most naturally lose confidence in 
all methods based on the fat-test and go back to 
the weight-of-milk system. Those who produce 
poor milk take advantage of such an opportunity 



PAYING FOR MILK FOR CHEESE-MAKING 269 

to Upset the entire system based on the fat-test. 
Thus, the whole situation has been needlessly con- 
fused, rather than benefited, for the average cheese- 
factory patron. 

PAYING FOR MILK ON BASIS OF FAT AND 

CASEIN 

By this method the percentages of fat and casein 
in each patron's milk are added and the figures 
thus obtained are used in apportioning dividends, 
as in the fat basis. This can be illustrated as fol- 
lows : 

We will make use of the figures already 
employed in illustrating the other methods. One 
patron furnishes milk containing 3 per cent of fat 
and 2.1 per cent of casein; the other, milk with 
4 per cent of fat and 2.5 per cent of casein. Each 
furnishes 100 pounds of milk; the total amount of 
cheese made is 18.9 pounds, realizing 189 cents. 
We add together the amounts of fat and casein in 
the two milks, obtaining 11. 6 as the total number 
of pounds of fat and casein in the 200 pounds of 
milk. The total amount of money received for the 
cheese is divided by the total amount of casein and 
fat, which gives us 16.3 cents as the value of each 
pound of mixed fat and casein in milk. The divi- 
dend of the patron furnishing the poorer milk Is 
16.3X5-1, which equals ^;^ cents; the dividend of 
the other is 16.3X6.5, which equals 106 cents. In 
this case, each receives the same price for the 
cheese, 10 cents a pound, but not the same for milk- 
fat; the poorer milk receives 27.7 cents a pound 



2/0 SCIENCE AND PRACTICE OF CHEESE-xMAKING 

lor its fat; the richer milk, 26.5 cents. Below are 
given in tabulated form the results of this and other 
methods already considered, and also the modification 
of the fat-and-casein basis, in accordance with the 
relative-value suggestions of Dr. Babcock ; that is, we 
allow full value for fat and one-fourth value for 
casein (p. 264). 



Per cent 
of fat 

in 
milk 



Per cent 
ot 

casern 
in milk 



Pounds 

of 
cheese 



Divi- 
dend by 
fat and 



Divi- 
dend by 

fat 
method 



Dividend 

by fat and 

one-fourth 

casein 

(P. 264) 



Dividend 

by ''fat-l-2" 

method 



2.1 
2.5 





Cents 


Cents 


Cents 


8.30 


83 


81 


82 


10.60 


106 


108 


107 



Cents 

86 

103 



The fat-and-casein method has the following ad- 
vantages : 

( 1 ) It is an accurate measure of the yield of cheese 
in the case of all kinds of milk when the losses of milk 
constituents are not excessive. 

(2) The temptation to adulterate by watering is 
entirely removed. 

The following disadvantages suggest themselves : 
(i) Assuming that a test for casein gives results 
as accurate as the Babcock test for fat in the hands 
of ordinary cheese-makers, it is objected that the test 
involves extra labor on the part of the cheese-maker, 
for which he cannot well afford the time. The same 
objection is often made against the Babcock test, and 
it would, of course, be much more forceful in regard 
to a casein-test. 

(2) An extra test involves additional cost, 
even in case a cheese-maker could find time to 



PAYING FOR MILK FOR CHEESE-MAKING 27I 

make both fat and casein tests. If a cheese-maker 
were paid oil tht basis of what is received for 
making- fat-tests, it would amount to $50 or $60 a 
season for most cheese-factories. To this must be 
added cost of materials and breakage of glassware, 
which might be conservatively placed at $10 to $15. 
There would thus be a total outlay on the part of the 
patrons amounting to $60 to $75 for the season in 
having the casein-test made. 

(3) The fat-and-casein method does not recog- 
nize any difiference in the value of cheese made 
from milk high and low in percentage of fat. It 
places the market value of casein on an absolute 
level with milk-fat, while Dr. Babcock gives milk- 
fat in cheese a value 6.6 times that of casein (p. 
262). 

(4) The use of the fat-and-casein method offers 
a temptation to remove fat from milk or to add 
skim-milk, in case of milk to be used for cheese- 
making. To illustrate, casein in skim-milk has a 
market value for the dairyman not to exceed 2 or 
3 cents a pound, while milk-fat is worth about 30 
cents a pound. In good cheese, casein and fat 
together bring about 18 cents a pound. If casein 
is paid for on a par with fat, then by adding skim- 
milk to normal milk, one can increase the price of 
his skim-m'ilk casein about nine times. The same 
would be true if fat were removed from milk and 
sold as butter or cream. In whatever manner one 
increases the ratio of casein to fat in milk, he in- 
creases the dividend value of casein in cheese-making, 
when fat a.n'd- casein are treated as of equal value in 
making dividends. 



272 SCIENCE AND PRACTICE OF CHEESE-MAKING 

(5) The fat-and-casein method requires more time 
in calculating dividends. 

(6) Some have expressed the fear that, under 
this system, the increased value of casein would 
lead dairymen to breed cows for milk high in casein, 
and that this would result in a poorer quality of 
cheese and general consequent danger to the cheese 
industry. In fact, the use of cows giving milk with 
a high casein content has been specifically empha- 
sized by some as a desirable end to work for and 
it is urged that such an aim would be realized by 
the recognition of casein in cheese-making as of 
equal value with fat. Assuming that the percent- 
age of casein in milk could be notably increased in 
an economical manner, what would be the result? 
By referring to pages 231-237, it can readily be 
seen that the process would be nothing more or 
less than a system of adding skim-milk to normal 
milk, thereby increasing the amount of casein in 
milk relative to fat. This fact is probably not 
fully appreciated by those who are advocating the 
process. We have probably reached the limits of 
safety, in more than one sense, in many strains of 
Holsteins and Ayrshires, as regards the high re- 
lation of casein to fat. We do not need to spend 
time and energy to breed cows for milk in the 
direction of skim-milk for cheese-making. Some 
progressive dairymen are, happily, still so old- 
fashioned in their ideas as to advocate the opposite 
process, viz., increasing the yield of fat in milk 
without paying any attention to its skim-milk con- 
stituent, casein. This is simply raising the old 
question that used to be discussed so much 20 years 



PAYING FOR MILK FOR CHEESE-MAKING 2/3 

and more ago regarding the ''butter cow" and the 
"cheese cow." Thus, in the 1892 report of the 
Vermont experiment station (pp. 122, 123), this whole 
question is ably discussed, the article closing as 
follows : "The logical conclusion, then, is that the 
so-called 'cheese cow,' that is, the cow which is 
especially good for cheese rather than for butter, 
does not exist, and that whenever a cow is found 
that is good for cheese-making purposes, the milk 
of that cow is equally good for the manufacture of 
butter." The following statement is found on page 
471 of the 1895 yearbook of the United States De- 
partment of Agriculture, in an article by the late 
Henry E. Alvord : "Cumulative evidence is un- 
necessary. These important truths are established, 
namely: The best milk makes the best cheese, and 
the most of it ; the milk which is most profitable 
for butter is also the most profitable for cheese ; 
the best butter cow is the best cheese cow." In a 
discussion of the same subject, Bulletin No. 9 of 
the New Hampshire station contains the following 
statements : "We are told that cows which are 
giving milk poor in fat and are therefore poor but- 
ter cows are great cheese cows. ... A milk 
rich in fat is not only a good milk for butter but 
also a good milk for cheese, while the reverse is also 
true." 

In harmony with the general tenor of the pre- 
ceding statements, the investigation carried on with 
different breeds of cows at the New York experi- 
ment station appears to demonstrate clearly that a 
pound of cheese-solids can be produced at less 



274 SCIENCE AND PRACTICE OF CIIEESE-MAKING 

cost in case of milk rich in fat than in case of milk 
poor in fat. 

(7) Another highly important question has 
been raised in connection with the use of a casein- 
test in paying for milk at cheese-factories — Is it 
worth the time and trouble expended on it? It 
is not worth the time, if, with Dr. Robertson, Dr. 
Babcock and others, we believe that casein is not 
equal in value to fat for cheese production in rela- 
tion to composition and quality of cheese. If, on 
the other hand, we believe that yield of cheese 
alone should be considered and that fat and casein 
are of equal value, pound for pound, in cheese pro- 
duction, even then we can ask the question — Are 
the differences caused by variation in casein worth 
the trouble and expense involved in making a 
casein-test in addition to fat? To what extent 
will dividends be readjusted among patrons and 
in what manner? While this question can not 
be answered finally until results have been secured 
in numerous factories, we have sufficient data on 
hand to give a definite answer in the case of one 
representative New York factory for one season. 
We have fat and casein determinations during one 
factory season for each of 50 different herds of 
cows whose milk was taken to one cheese-factory. 
The analyses of milk were made every other week 
for each herd separately from May to October in- 
clusive. In 23 cases, the fat-and-casein method 
gave a larger dividend than did the fat alone by 
an average of 1.6 cents for each 100 pounds of milk, 
the greatest difference in the case of any one patron 
being 5.9 cents, and the least o.i cent. In one 



PAYING FOR MILK FOR CHEESE-MAKING 275 

case, both methods gave the same result. In 26 cases, 
the fat method gave higher results by an average 
of 1.4 cents for 100 pounds of milk, the difference 
varying in the case of different individuals from 5.1 
cents to 0.1 cent. 

The greatest difference found in favor of the 
fat and casein basis, 5.9 per cents per 100 pounds of 
milk, would mean for an entire factory season 
nearly $20, assuming that this patron furnished 
33,600 pounds of milk, an average of 224 pounds 
for 150 days, which was the actual average for 
each patron. Summarizing the results on this basis, 
we have 2;^ men receiving more money by the fat- 
and-casein method, amounting altogether, for the 
season, to $123.46, the increased dividends of each 
varying from 33.6 cents to $19.83, and averaging 
$5.39. As a matter of fact, about two-thirds of the 
money would go to 8 patrons. One patron re- 
ceives the same amount either way. The remain- 
ing 26 patrons receive less by the fat-and-casein 
method than by the fat basis, amounting altogether 
to $123.46, varying from 33.6 cents to $17.13, and 
averaging $4.75 each. 

On the basis of the estimated cost of $60 to $75 
spent in paying for the test, more than half of the 
difference ($123.46) would be used up, so that, if 
those who benefited by the casein-test paid for it, 
there would be distributed not more than half of 
the amount above given. This would mean an ex- 
penditure of $60 to $75, in order to adjust a dif- 
ference of $123 in the interest of 23 men who fur- 
nish milk which tests below the average in fat. 
The entire sum involved amounts to less than 0.4 



2^6 SCIENCE AND PRACTICE OF CHEESE-MAKING 

per cent of the factory's receipts from cheese. 
Under such circumstances, it is not at all likely 
that the 2^ patrons would vote to employ the fat- 
and-casein method in distributing dividends, nor is 
it likely that most of the 2^^ men benefited would 
ask it, when the high relative cost of making a 
redistribution was understood. While the results 
represent only one cheese-factory, the conditions 
are t}pical of those prevailing in New York state, 
and results that are strikingly different from these 
would probably be exceptional. If the dividends 
were made on the basis of allowing less for casein 
than fat, as recommended by Dr. Babcock (p. 264), 
the difference in favor of the patrons furnishing 
extra casein would be less than one-quarter what 
they are when - we allow the same price for casein 
as for fat. On such a basis, the difference would 
be only about half the cost of making the casein- 
tests. 

PAYMENT ON BASIS OF FAT AND CAL- 
CULATED CASEIN 

In view of the fact that so many cheese-fac- 
tories are still paying for milk on the basis of 
weight alone, as a result of the confusion that has 
been created in regard to the fairness of the fat 
basis, a method might be suggested which would 
find use in factories that are now using no test 
system, which would be far superior to the weight- 
of-milk method and at the same time possess certain 
advantages over other modifications of the fat 
basis. Such a method would be to pay on the basis 



PAYING FOR MILK FOR CHEESE-MAKING 2']"/ 

of the fat and of the casern calculated according to 
the formula, (Fat — 3)Xo.4H-2.i. Such a method 
is not recommended where the fat basis is being 
used, but only as a compromise where it comes to 
a choice between some such basis and the weight- 
of-milk method; in other words, where the preju- 
dice against the fat basis is too strong to be over- 
come. The amount of casein obtained thus is 
added to the fat and the dividends calculated in the 
manner given on p. 284. The use of a method 
basing dividends on the fat-test and the amount of 
calculated casein would possess the following ad- 
vantages : 

(i) It would be preferable to the fat-and-casein 
method, which requires two separate tests to be made, 
since no test would be needed for casein, but only 
for fat. It would, therefore, involve no additional 
expense of time, labor or money, as is the case with 
the casein-test. 

(2'* It would be more fair than the "fat-plus- 
two" method, because milk containing higher per- 
centages of fat would receive payment for the in- 
creased amount of casein that goes with that 
increased percentage of fat, instead of receiving 
credit for only 2 per cent of casein, rich and poor 
milks alike. This method gives results that are in 
most cases much closer to the yield of cheese than 
the "fat-plus-two" method. 

(3) The watering or skimming of milk could not 
affect the results, because the casein is made to depend 
on the fat content. In this respect the method is 
much superior to the fat-and-casein or the fat-plus- 
two method. 



2"/^ SCIENCE AND PRACTICE OF CHEESE-MAKING 

(4) No more labor need be involved than in 
the case of the fat basis, either in the matter of 
testing or in the matter of calculating dividends. 
The matter can be simplified by the consultation of 
a table, which can be made out once for all. The 
following formula, can be used in preparing such 
a table: 

(Fat — 3)Xi4+5-io=Amount of fat -and casein in 
100 pounds of milk. 

Such a table, already prepared, is here given : 



Per cent of 


Dividend 


Per cent of 


Dividend 


fat in milk 


number 


fat in milk 


number 


3.00 


S.IO 


4.05 


6.57 


3.05 


5.17 


4.10 


6.64 


3.10 


5.24 


4.15 


6.71 


^ 3.15 


5.31 


4.20 


6.78 


3 20 


5.38 


4.25 


6.85 


3.25 


5.45 


4.30 


6.92 


3.30 


5.52 


4.35 


6.99 


3.35 


5.59 


4.40 


7.06 


3.40 


5.66 


4.45 


7.13 


3.45 


5.73 


4.50 


7.20 


3.50 


5.80 


4.55 


7.27 


3.55 


5.87 


4.60 


7.34 


J. 60 


5.94 


4.65 


7.41 


3.d5 


6.01 


4.70 


7.48 


3.70 


6.08 


4.75 


7.55 


3.75 


6.15 


4.80 


7.62 


3.80 


6.22 


4.85 


7.69 


3.85 


6.29 


4.90 


7.77 


3.9b 


6.36 


4.95 


7.84 


3.95 


6.43 


5.00 


7.90 


4.00 


6.50 







(5) The introduction of the fat-test is called for 
by this method, and thus a great step in advance 
would be made in compari.son with the weight-of- 
milk method. This might ultimately lead to the adop- 
tion of the simple fat basis. 

The following objections to such a method may be 
suggested : 



PAYING FOR MILK FOR CHEESE-MAKING 279 

(i) It aims to pay for the amount of cheese 
produced without regard to composition or quaUty. 
Of course, this same objection appHes to the fat-and- 
casein method and the fat-phis-two method. 

(2) The method of calculation may give 
amounts of casein differing from those actually 
present in milk. In individual cases and for single 
tests, this might be true, but, taking the average 
of a whole season, the differences would not 
usually be found great, and the season's average 
would be the factor on which to base a comparison 
as to accuracy. As a matter of fact, in the case 
of the 50 herds already referred to, in no case was 
there a difference in the season's results greater 
than 0.25 per cent of casein between the calculated 
amount and that obtained by the chemical method ; 
while in the case of 40 out of 50 patrons the results 
differed by less than o.i per cent, in several cases 
being identical. The casein-test, even in skillful 
hands, may give results that differ as much as 0.2 per 
cent from the regular chemical method. 

METHODS OF CALCULATING DIVIDENDS 
AT CHEESE-FACTORIES 

In concluding this chapter, we will illustrate 
somewhat more in detail how dividends at cheese- 
factories are calculated according to the different 
methods that have been discussed. For this pur- 
pose, we will make use of the following data which, 
for convenience, are given here in a body for refer- 
ence. In all cases, the following three items must 
be known : ( i ) The amount of milk delivered by 



28o SCIENCE AND PRACTICE OF CHEESE-MAKING 

each patron during the dividend period; (2) total 
or gross amount of money received for the cheese 
produced during the same period; and (3) the ex- 
penses to be deducted from gross receipts, such as 
cost of manufacture, cheese-boxes, cartage, selling, 
etc. 



Name 

of 
patron 


Pounds of milk 
delivered dur- 
ing dividend 
period 


Pounds of 

cheese for 

100 pounds of 

milk 


Per cent 

of fat 

in milk 


Per cent 

of casein 

in milk 


Pounds of 
cheese made 

from milk 
delivered by 
each patron 


A 
B 
C 
D 

E 


350 
650 
835 
965 
1200 


10.6 
9.7 
13.3 
11.5 
11.1 


4.0 
3.6 
5.2 
4.4 
4.2 


2.50 
2.34 
2.98 
2.68 
2.58 


37.1 

63.0 

111.0 

111.0 

133.2 


Totals 


4000 








455.3 



From the stated amounts of milk there are made 
455.3 pounds of cheese. We will suppose that this 
is sold at a price which realizes 10 cents a pound, 
or $45.53, after all expenses are deducted. 

Calculating dividends on basis of weight of milk. 

— In the table preceding we have a total of 4,000 
pounds of milk furnished in the dividend period 
and the cheese made from this nets $45.53. Divid- 
ing this sum of money by the number representing 
the pounds of milk delivered (4,000), we find the 
net receipts from i.o pound of milk to be 1.138 
cents. This amount is multiplied by the number 
representing the pounds of milk furnished by each 
patron and the result gives the amount of the divi- 
dend of each. The results are given in the following 
table : 



PAYING FOR MILK FOR CHEESE-MAKING 



281 











Pounds 










Value 


Divi- 


of cheese 


Money- 


Money re- 


Name 


Pounds 


of 1.0 


dend of 


made from 


received 


ceived for 


of 


of milk 


pound 


each for 


milk fur- 


for each 


each pound 


patron 


delivered 


of milk 


period 


nished by 
each 


pound of 
cheese 


of milk-fat 
furnished 






Cents 






Cents 


Cents 


A 


350 


1.138 


$3.58 


37.1 


10.73 


28.4 


B 


650 


" 


7.40 


63.0 


11.75 


31.1 


C 


835 


" 


9.51 


111.0 


8.57 


21.9 


D 


965 


" 


10.98 


111.0 


9.90 


25.9 


E 


1200 




13.66 


L33.2 


10.26 


27.1 



The figures in the last two columns emphasize the 
fact that this method of paying for milk gives results 
that have little or no relation to the cheese-produc- 
ing values of the milk. It is fair to all only when 
the milk furnished by each patron is of the same 
composition and cheese-producing value as the milk 
of every other patron, a condition rarely, if ever, found 
to exist. 

Calculating dividends on basis of fat in milk. — 
Having the data already given above in the table on 
p. 280 we multiply the amount of milk-fat delivered 
by each patron by the net price realized for one pound 
of fat. We will consider the method in three separate 
steps. 

Step I. To find the number of pounds of milk-fat 
furnished by each patron, multiply in each case the 
weight of milk by the number indicating the per cent 
of fat and divide the result by 100. 

Step 2. Find the net value of one pound of milk- 
fat by dividing the total net receipts by the total num- 
ber of pounds of fat delivered by all the patrons 
during the dividend period. 



282 SCIENCE AND PRACTICE OF CHEESE-MAKiNG 

Step 3. Multiply the number of pounds of fat de- 
livered by each patron by the net price received for one 
pound of fat. 

Example: Step i. The data and results are indi- 
cated in tabular form, as follows : 



Name of 
patron 


Pounds of milk 
delivered during 
dividend period 


Per cent 

of fat 

in milk 


Pounds of fat 

in milk 

delivered 


A 


350 
650 
835 
965 
1200 


X 4.0 
X 3.6 
X 5.2 
X 4.4 
X 4.2 


= 14 00 


B 

C 

D 

E 


= 23.40 
= 43.42 
= 42.46 
= 50.40 


Tot.al number of pounds of fat delivered by all patrons . . 


173.68 



Step 2. From the amount of milk indicated above, 
the amount of cheese made w^as 455.3 pounds, which 
realized 10 cents a pound after deducting all ex- 
penses, making a total of $45.53. This sum divided 
by 173.68, the total pounds of fat delivered, gives 
26.2 cents as the net price received for each pound 
of fat. 

Step 3. The data and results are indicated in 
tabular form, as follows : 



Name of 
patron 


Pounds 

of fat 

delivered 


Net price re- 
ceived for fat 
per pound 


Amount of 
dividend due 
each patron 


Net price re- 
ceived for 
cheese per lb. 


A 


14.00 
23.40 
43.42 
42.46 
50.40 


Cents 
X 26.2 
X 26.2 
X 26.2 
X 26.2 
X 26.2 


= $ 3.67 
6.14 
= 11.38 
= 11.13 
= 13.21 


Cents 
9.90 


B 


9.75 


C 

D 


10.25 
10.03 


E 


9.92 







PAYING FOR MILK FOR CHEESE-MAKING 



283 



Calculating dividends on basis of yield and rela- 
tive value of cheese-solids. — By this method one 
proceeds exactly as in case of the fat-basis method, 
except that in place of the percentages of fat, one 
uses the number obtained from the table (p. 262) cor- 
responding in each case to percentage of fat in milk 
and the lactometer reading. 

Calculating dividends on basis of milk-fat plus 
two. — The following table indicates the general method 
of procedure : 



Name 

of 
patron 



A 
B 
C, 
D 
E 



Pounds 
of milk 

de- 
livered 
during 
divi- 
dend 
period 



Per cent of 
fat in milk 
+ 2 (casein) 



Pounds 
of fat 

and 
casein 

ftir- 
nished 
corre- 
spond- 
ing to 
fat + 2 



350 
650 
835 
965 
1200 



X (4.0x2 = )6.0 
X (3.6x2=)5.6 
X (5.2X2=)7.2 
X (4.4x2 = )6.4 
X (4.2x2=)6.2 



21.0 
36.4 
60.1 
61.8 

74.4 



Price 


Amount 


of each 


of divi- 


pound 


dend 


of fat 


due 


and 


each 


casein 


patron 



Net 
price re- 
ceived 

for 
cheese 

per 
pound 



X 


17.95 


= $3.77 


X 


17.95 


= 6.54 


X 


17.95 


= 10.78 


X 


17.95 


= 11.10 


X 


17.95 


= 13.34 



Cents 
10.16 
10.40 
9.71 
10.00 
10.02 



Net 
price re- 
ceived 
for fat 

per 
pound 



Cents 
27.0 
28.0 
24.8 
26.1 
26.5 



In explanation of the foregoing table, it is seen 
that the amount of milk furnished by each patron is 
multiplied by the per cent of fat plus two. These 
results are added and the sum (amounting to 
253.7) divided into the amount of money received 
for the cheese ($45.53), giving 17.95 cents as the 
value of each pound of mixed fat and casein (rep- 
resented by 2 pounds of casein in 100 pounds of 
milk). The number, obtained in each case by mul- 
tiplying the number of pounds of milk furnished by 



284 SCIENCE AND PRACTICE OF CHEESE-MAKING 

the number representing the per cent of milk-fat-|-2, 
is then multipHed by 17.95, the result being the 
dividend in each case. It is noticed that this method 
makes a pound of cheese or of milk-fat yield larger 
money returns in case of poor than in case of rich 
milk. 

Calculating dividends on basis of fat and casein. 
— The same process is followed as before, except 
that the yield of fat and casein, taken together, con- 
stitutes the basis of division. The percentages of 
fat and of casein in milk are added together, in each 
case, and the sum multiplied by the number of 
pounds of milk furnished, thus giving the number 
of pounds of fat and casein furnished by each patron. 
The total amount of fat and casein furnished by all 
the patrons for the dividend period (279.36 pounds) 
is divided into the net proceeds from the sale of cheese 
and the result is the net dividend value (16.3 cents) 
of one pound of mixed fat and casein. This figure 
is then multiplied by the amount of fat and casein 
furnished by each patron. The details are indicated 
below. 



Name 

of 
patron 



Pounds 
of milk 

delivered 
during 

dividend 
period 



Per cent of 
fat and 
casein 
in milk 



Pounds of 
fat and 
casein 

furnished 



Amount 


Net 


of divi- 
dend 
due 
each 


price 
received 

for 
cheese 


patron 


per 
pound 



Net 

price 

received 

for fat 

per 
pound 



A... 
B... 
C... 
D.. 
E... 



350 
650 
835 
965 
1200 



X(4.0X2.50=)6.50 
X(3.6x2.34=)5.94i 
X(5.2X2.98=)8.18! 
X(4.4X2.68=)7.08 
x(4.2x2.58=)6.78; 



= 22.75x16.3 = 
= 38.61x16.3 = 
= 68.30x16.3 = 
= 68.32X16.3 = 
= 81.38X16.3 = 



$3.71 
6.29 
11.13 
11.14 
13.26 



Cents 
10.00 
10.00 
10.00 
10.00 
10.00 



Cents 
26.5 
26.8 
25.6 
26.2 
26.3 



CHAPTER XXII 

The Relations of Micro-Organisms and 
Enzyms to Cheese-Making 

Milk, on standing- under ordinary conditions, under- 
goes a variety of changes sooner or later, many of 
which destroy its value for cheese-making purposes. 
The most common and extensive changes occurring 
in milk are due to fermentations. One result of some 
kinds of fermentation is the production of bad flavors, 
but these may be acquired also by direct absorption 
from the surrounding air or from the food consumed 
(p. 6). We shall see that certain kinds of fermenta- 
tions are useful and necessary in cheese-making, while 
others make it difficult or impossible to prepare a good 
product. 

FERMENTATIONS AND FERMENTS 

The souring of milk is one of the most familiar 
cases of fermentation. The important change taking 
place is the formation of lactic acid from milk-sugar 
and the change is caused by certain livi;ig organisms. 
An equally familiar case of fermentation is the 
coagulation of milk by rennet-extract. In this case 
the change is produced, not by a living organism, but 
by a chemical substance. That which causes fermenta- 
tion is called a ferment. 

Fermentation may be defined as a chemical change 
of an organic compound through the action of living 

285 



286 SCIENCE AND PRACTICE OF CHEESE-MAKING 

organisms or of chemical agents. We thus have two 
general kinds of ferments, (i) organized ferments 
and (2) unorganized ferments, known also as chem- 
ical ferments or enzyms. In the illustrations given 
above, the ferments are (i) lactic acid organisms and 
(2) rennet ferment; in one case the organic matter 
ohanged is milk-sugar; in the other, milk-casein. 
Organized ferments are living micro-organisms, 
capable, as a result of their growth, of causing fer- 
mentations. Unorganized ferments are chemical sub- 
stances, or ferments without life, capable of causing 
marked changes in many complex organic compounds, 
the enzyms themselves undergoing little or no change. 

General characteristics of ferments. — Ferments 
possess certain general characteristics in* common, 
among which may be mentioned the following : ( i ) 
A very small amount of ferment is capable of pro- 
ducing very great changes. (2) They are all de- 
pendent upon temperature as a condition of activity. 
They cease to act at low and also at high tempera- 
tures. Most of them find the temperature that is 
best suited to» their greatest activity between 80° and 
100° F. (3) Ferments are destroyed by heat, the 
temperature of boiling water, in most cases, com- 
pletely destroying their power to act. Their activity 
is checked by low temperatures, but, when again 
warmed, they renew their activity. (4) The action 
of ferments Is checked or prevented by many sub- 
stances. (5) When the products formed by ferments 
accumulate in certain amounts, the ferment action 
usually stops. (6) All ferments are closely con- 
nected with living processes. 

Organized ferments, or living micro-organisms 
capable of causing fermentations, are divided into 



MICRO-ORGANISMS AND ENZYMS 28/ 

several classes; but those of greatest interest in con- 
nection with cheddar cheese-making are called bac- 
teria. These are the smallest conceivable forms of 
plant life. Each individual consists of a single cell, 
averaging in diameter one-thirty-thousandth of an 
inch. 

(i) Kinds. — Bacteria appear in three general 
varieties of form: '(a) Ball (coccus), (b) short rod 
(bacillus), and (c) corkscrew (spirillum). (Figs. 
39-42.) 




FIG. 39 — BALL-SHAPED BAG- FIG. 40 — CHAINS OF EALL- 

TERIA (coccus). SHAPED (cOCCUS) BAC- 

( Rogers) teria 

(Rogers) 

(2) Method of grozvth and reproduction. — They 
multiply in number, or reproduce, by simple division ; 
that is, when a cell grows in size, it increases more 
in one direction, so as to result in lengthening out 
slightly, and a partition forms across the cell, thus 
producing two new cells in place of the old one ;■ and 
then each of these subdivides again and so on con- 
tinuously. Some kinds of bacteria form spores in 
the cells ; these are to bacteria what seeds are to 



288 SCIENCE AND PRACTICE OF CHEESE-MAKING 



higher plants. Spores are not so easily killed by heat 
as are bacteria. Under favorable conditions, the 
rapidity of growth of bacteria is remarkable. Thus, 
in some cases, one cell divides into two cells in 2Q 
minutes; if this rate were kept up for 24 hours, the 
one cell would multiply into several millions. 

(3) Food requirements of bacteria. — Bacteria re- 
quire as food for satisfactory growth compounds con- 
taining nitrogen, carbon, hydrogen and, in addition, 




FIG. 41 — ROD-SHAPED BAC- 
TERIA (bacillus). CLEAR 
AREAS IN SOME ARE 

SPORES. (Rogers) 



FIG. 42 — B A C T E R 1 A WITH 
HAIR-LIKE ORGANS, WHICH 
THEY USE IN MOVING 
THEMSELVES ABOUT IN 

LIQUIDS (Rogers) 



small amounts of inorganic or mineral matter. The 
sugar, casein, albumin and salts in milk and its 
products furnish a supply of food very readily 
utilized by bacteria. 

(4) Temperature. — The bacteria commonly pres- 
ent in milk grow between the limits of 40° and 110° 
F., the most favorable limits being between 80° and 
95° F. Many bacteria are killed between 130° and 



MICRO-ORGANISMS AND ENZYMS 289 

140° F., when exposed to this heat for ten minutes, 
and most of them are destroyed at 185° F. Many 
spores are killed at temperatures only above 212° 
F., and even then require heating one to three hours. 
(Fig. 43.) Dry heat is less effective than moist heat. 
Live steam, therefore, affords a most effective means 
of destroying bacteria. All bacteria are rendered in- 
active at low temperatures and some may be killed 
by intense cold. Many bacteria may retain life on 
being dried and become active again when placed 
under favorable conditions of moisture and tem- 
perature. 

(5) Action of sunlight, chemicals, etc. — Sunlight 
kills many bacteria when they are exposed directly 
to the sun's rays for a few hours. Bacteria are either 
checked in growth or killed by many different chem- 
ical compounds. Those compounds that simply 
retard the rapidity of growth of bacteria are called 
antiseptics, among which are carbolic acid, salt, salt- 
peter, etc. ; those that destroy bacterial life are called 
disinfectants, among which are mercuric chlorid (cor- 
rosive sublimate), formaidehyd (formalin), potas- 
sium bichromate, chloroform, etc. The activity of 
each kind of bacteria is stopped by an accumulation 
of products formed by it and, in some cases, by the 
products of activity of other bacteria. Thus, most 
kinds of lactic acid bacteria stop growing when about 
0.9 per cent acid is formed, and much less than this 
amount of lactic acid also prevents the growth of 
many other bacteria. 

(6) Changes produced. — In the course of their 
growth, bacteria produce great changes in the 
materials in which they grow ; and the process by 
which these changes are brought about are known, 



290 SCIENCE AND PRACTICE OF CHEESE-MAKING 



It 



WATER eorLS 212- 
BLOOD HEATw- 



=Q 



WATER FREEZES 32. 



ALL GROWING BACTeRIA 
J KILLED^ 

-GROWTH CEASES. 



^--GROWTH MOST RAPID. 



-GROWTH RETARDED. 



__i5R0WTH CEIASES. 



FIG. 43 — INFLUENCE OF TEMPERATURE ON BACTERIA ORDINARILY 

FOUND IN MILK (Rogers;. 



MICRO-ORGANISMS AND ENZYMS 29I 

as previously stated, under the general name of fer- 
mentation. 

(7) Distribution. — Bacteria are found distributed 
nearly everywhere in the soil, in the air and in v^ater. 
They are always present in large numbers wherever 
vegetable or animal matter is undergoing decay. They 
are, therefore, always closely associated with dirt and 
filth. While some are the causes of dreaded diseases 
and of serious troubles in cheese-making, most of 
them are either harmless or actively helpful in many 
ways. 

Unorganized ferments or enzyms. — Many enzyms 
are produced directly by bacteria and are the direct 
agents producing the observed changes of bacterial 
activity, while many are formed in higher plants and 
in animals. Thus, the pepsin found in the human 
stomach is an enzym ; its special power or form of 
activity enables it to change protein compounds from 
insoluble to soluble forms. The ptyalin contained in 
saliva is another enzym and is capable of changing 
starch into sugar. Enzyms are destroyed by high 
temperatures and by many disinfectants. Some sub- 
stances, like ether, chloroform and formaldehyd, do 
not seriously interfere with the activity of enzyms, 
while they do destroy bacteria. 

In connection with the subject of ferments, we 
shall consider the following ones as those of most 
importance in connection with cheese-making: (i) 
Lactic acid bacteria, (2) gas-producing bacteria, (3) 
digesting bacteria, (4) bacteria producing undesir- 
able flavors, (5) yeasts, (6) milk-enzyms, (7) rennet- 
enzyms, and (8) pepsin. The ferments that are 



292 SCIENCE AND PRACTICE OF CHEESE-MAKING 



responsible for many of the defects found in Amer- 
ican cheddar cheese will be discussed only briefly here, 
because their relations to cheese-making are fully 
treated from a practical standpoint in Part II, pp. 
I 15-130. 

LACTIC ACID FERMENTATION 

The ordinary souring of milk is due to the forma- 
tion of lactic acid, which is produced by the action 
of lactic acid bacteria (Bacillus lactici acidi. Fig. 44) 
upon the sugar in milk. A large number of different 

kinds or types of bacteria 
are able to produce lactic 
acid from milk-sugar. 
Some interesting work 
has been done recently 
(Bull. No. 42, Mich. 
Agr. Coll. Exp. Sta.) 
which shows that other 
micro-organisms are often 
associated with the micro- 
organisms of lactic fermen- 
tation and that these 
associate micro-organisms 
often have the power of furnishing products that 
exert a decided influence upon the rapidity of the 
growth of the lactic micro-organisms. 

We have already (p. 150) called attention to 
the fact that the sour taste of milk is not due to the 
presence of uncombined lactic acid, since little or no 
free lactic acid is present in sour itiilk until it has 
quite a high degree of acidity ; but is due to acid phos- 
phate of calcium, which is formed by the action of 
lactic acid upon the insoluble calcium compounds in 




FIG. 44 — TYPICAL LACTIC- 
ACID BACTERIA (RogCrs) 



MICRO-ORGANISMS AND ENZYMS 293 

the milk. Milk begins to taste sour when its acidity 
amounts to about 0.3 per cent ; which really means 
when a little over 0.2 per cent of lactic acid has been 
formed from milk-sugar ; because the milk-casein 
itself and the soluble phosphates have an acidity of 
nearly o.io per cent (p. 153) when the milk is 
freshly drawn and no milk-sugar has had a chance 
to be changed into lactic acid. According to recent 
work done at the New York experiment station, 
milk curdles on boiling where the acidity reaches 
0.32 to 0.46 per cent, and at ordinary room tempera- 
ture when it reaches 0.58 to 0.72 per cent. When 
artificial lactic acid is added directly to fresh milk, 
curdling takes place on boiling when the acidity 
reaches 0.36 per cent and at room temperature when 
the acidity reaches 0.57 per cent. Bacteria continue 
actively converting milk-sugar into lactic acid, 
until the amount of acid reaches 0.8 to i.o per cent 
of the milk; and then they greatly diminish or cease 
their activity, because they cannot thrive in a solu- 
tion showing this amount of acidity. Their activity 
is thus stopped by the accumulation of the chief 
product of their own activity, and not because the 
supply of milk-sugar runs out ; for, when their 
activity ceases, about three-quarters of the milk- 
sugar remains still unconsumed. Products besides 
lactic acid are formed, varying according to tem- 
perature and other conditions. In recent work at 
the New York experiment station, we have ob- 
tained, in the form of lactic acid, about 80 per cent 
of the milk-sugar that was decomposed. In connec- 
tion with cheese-making, the total acidity of the whey 
may rise as high as 1.2 per cent. Under conditions, 
which are not present in cheddar cheese-making, 
some micro-organisms may produce as much as 3 



294 SCIENCE AND PRACTICE OF CHEESE-MAKING 

per cent of lactic acid, decomposing a correspond- 
ing- amount of milk-sugar. 

The range of temperature most favorable to lactic 
acid organisms is 90° to 95° F. Below 80° F. their 
activity gradually decreases and practically ceases at 
50° F. At 105° F., they are fairly inactive; many 
are killed at 135° to 140° F., and all at 150° to 
160° F. 

While the lactic acid fermentation spoils milk for 
the taste of most people, at least for ordinary uses, it 
is a very essential factor in the manufacture of cheese. 
Very few lactic acid bacteria are found in fresh milk, 
but they increase so rapidly at ordinary temperature 
(70° F.) that in 12 to 18 hours they generally exceed 
in number all other bacteria in milk. In summer 
weather, when the temperature is especially favorable 
to their rapid growth, the lactic acid bacteria usually 
constitute, at the time the milk sours, more than 95 
per cent of all the micro-organisms in the milk. 

While the growth of lactic acid organisms in milk 
is favored by the presence of a small amount of acid, 
most other organisms do not thrive so well in an acid 
environment. Therefore, as soon as enough milk- 
sugar has been converted into lactic acid to produce 
a slightly acid condition, other organisms decrease 
in activity, while the lactic acid organisms vigorously 
increase, unhindered. It is quite commonly thought 
that milk is peculiarly liable to sour during thunder- 
storms, as the result of some peculiar electrical con- 
dition or other mysterious influence. The hot weather 
preceding such storms favors the more rapid growth 
of the lactic acid bacteria and this is a sufficient ex- 
planation, and the proper one. Milk free from such- 
micro-organisms never sours during thunderstorms. 



MICRO-ORGANISMS AND ENZYMS 295 

The lactic acid fermentation we have been con- 
sidering is what we may call the normal form, the 
particular form we desire to have present in milk in 
cheese-making. Their presence is insured by the use 
of good starters (p. i8). Milk in which this form 
of lactic fermentation has occurred produces, in 
souring, a firm curd free from gas bubbles and with 
only a little whey on the surface. When agitated, 
the curd breaks apart readily into small particles, 
which settle slowly and leave a clear whey. The 
milk should have a pleasant, clean, acid taste, en- 
tirely free from anything resembling a tainted flavor. 
So far as we know, the lactic acid bacteria belonging 
to this normal group never form products of a poison- 
ous character. 

GAS-PRODUCING BACTERIA 

Some of the bacteria that decompose milk-sugar 
with formation of lactic acid are usually grouped with 
the lactic acid bacteria, though they possess distinguish- 
ing characteristics which mark them as abnormal, so 
far as their behavior in cheese-making is concerned. 
While they decompose milk-sugar and produce lactic 
acid, they produce other products besides, especially 
gases ; they may also produce volatile products that 
are offensive. These bacteria are responsible for many 
of the defects in cheese (pp. 116-130). When gas- 
producing ferments are present in milk, they are 
usually responsible for increased losses of fat in the 
cheese-making process. 

DIGESTING BACTERIA 

A large group of bacteria curdle milk without sour- 
ing it and then slowly digest or dissolve the curd; 



296 SCIENCE AND PRACTICE OF CHEESE-MAKING 

therefore, they are often called ''liquefiers." These 
effects are due to enzyms which are produced by the 
bacteria. Some of these bacteria form products that 
are offensive in flavor; some produce gases, and some, 
acid. They may be a source of serious trouble in 
cheese-making in the production of gassy curd and 
offensive flavors in cheese. They may also cause 
some dissolving of the curd, in which case the loss of 
fat is unusually large. These bacteria are widely dis- 
tributed, being found in stable filth, in soil, water and 
floating dust. They are nearly always present to some 
extent in milk. Fortunately, their activity is checked 
by the presence of lactic acid, and the easiest method 
of controlling such ferments in cheese-making is to 
make conditions favorable for the rapid growth of 
normal lactic acid bacteria ; this is usually accom- 
plished by the use of a pure starter. The growth of 
digesting bacteria in milk is favored by high tempera- 
ture; consequently, in hot weather, when the high 
temperature favors the growth of the digesting bac- 
teria more than it does the lactic acid organisms, the 
undesirable forms get beyond control and seriously 
impair the operations and results of cheese-making. 

BACTERIA PRODUCING UNDESIRABLE 

FLAVORS 

Different bacteria are responsible for many different 
kinds of bad flavors in milk and cheese, among which 
are the following: Bitter (p. 119), fishy, rancid or 
butyric acid, hydrogen sulphid (p. 116). 

YEASTS 

Yeasts are micro-organisms resembling bacteria in 
some respects, but usually larger. They are very 



MICRO-ORGANISMS AND ENZYMS 297 

widely distributed and are common in milk. The con- 
ditions usually present in milk are not favorable to 
their growth and they are not, therefore, the source 
of trouble so often as are bacteria. Among the effects 
which can be attributed to the action of different 
yeasts are the formation of bitter and of fruity flavors 
(pp. 118, 126). 

MILK-ENZYMS 

Milk contains several different enzyms. Some of 
them, at least, are of bacterial origin. It would take 
us too far from the purpose of this discussion to go 
into details relating to milk-enzyms. We shall con- 
fine our attention to the one known as galactase. In 
1897, Babcock and Russell announced the discovery 
of an unorganized ferment or enzym in milk to which 
they gave the name of galactase. They were led to 
this discovery by observing that fresh milk coagu- 
lates, even when obtained as free as possible from 
bacteria, and when all bacterial activity has been 
stopped by treatment with ether or chloroform. The 
milk first coagulates and then the curd gradually dis- 
solves. Having excluded the seeming possibility of 
bacterial action in the milk after it was drawn, they 
concluded that the observed coagulating and dissolv- 
ing action must be due to enzym action, probably two 
different enzyms. Galactase is probably a mixture 
of two or more different enzyms, since it has 
been shown that separator-slime, when treated accord- 
ing to Babcock and Russell's method in preparing 
galactase contains at least three distinct enzyms, 
galactase proper, peroxidase and catalase. The dis- 
tinctive feature of the action of galactase is its power 



298 SCIENCE AND PRACTICE OF CHEESE-MAKING 

to change insoluble proteins like milk-casein into 
soluble forms. 

The following have been given as some of the more 
prominent characteristics of galactase. ( i ) Galac- 
tase readily attaches itself to finely divided particles 
in suspension like milk-casein and fat-globules ; hence, 
it is found in separator-slime and in cream to a greater 
extent than in milk or skim-milk. (2) The most 
favorable temperature for the action of galactase lies 
between 98° and 108° F. Heated for ten minutes 
above 168° F., its activity is destroyed, as shown by 
the following table : 

EFFECT OF HEAT ON GALACTASE IN MILK 



Temperature used 
in heating milks 


Age of milks 

when 
analyzed 


Soluble nitrogen expressed 

in percentage of nitrogen 

in milk 


Degrees 
90°C.(194°F.) 
85°C.(185°F.) 
85^C.(185°F.) 
95°C.f203°F.) 
95°C.(203°F.) 
98°C.(208°F.) 


Months 
13 
8 
7 
15 
16 
14 


Per cent 
4.26 
10.8 
9.7 

5.52 
5.5 
11.5 



(3) Free acids, especially hydrochloric acid, retard 
the activity of galactase. Neutral or alkaline reac- 
tions favor its action. (4) Many disinfectants, like 
mercuric chlorid, carbolic acid, formaldehyd, carbon 
disulphid, etc., retard or prevent the action of galac- 
tase. (5) Its activity is greater in the early stage 
of working, as measured by the rapidity with which 
casein is 'changed into soluble compounds. 

As a result of their work, Babcock and Russell 
concluded that galactase is a trypsin-like ferment, 



MICRO-ORGANISMS AND ENZYMS 299 

except that one of its most distinctive characteris- 
tics is its abiHty to form, among other products, 
ammonia, and that, therefore, galactase plays a 
principal role in cheese-ripening. Their galactase 
work has been confirmed to the extent that there is 
in milk some enzym that causes more or less de- 
composition of milk-casein and of cheese paracasein 
in the presence of chloroform or ether. In work 
done at the New York experiment station, the ability 
of galactase to form ammonia was not confirmed 
either in case of milk or cheese. Cheese kept in an 
atmosphere of chloroform produced no ammonia or, 
at most, only slight traces even at the end of 15 
to 24 months. Samples of the cheese were sent to 
the Wisconsin experiment station, and the absence of 
ammonia was there confirmed. The view previously 
held to the efifect that galactase was able to account 
for most of the changes in cheese-ripening was then 
modified. 

RENNET-ENZYMS ' 

Rennet-extract contains one or two unorganized 
ferments or enzyms. There has long been a differ- 
ence of opinion as to whether there is in rennet-extract 
one enzym which acts in two different ways or two 
different enzyms, each with its own characteristic 
action. So far as the essential facts are concerned, 
rennet-extracts possess the power of effecting two 
distinct kinds of changes : ( i ) coagulation of milk- 
casein and (2) dissolving or digesting the milk-casein 
coagulum. Those who regard these two actions as 
due to two different enzyms contained in rennet call 
the -coagulating enzym rennin or chymosin, and the 



300 SCIENCE AND PRACTICE OF CHEESE-MAKING 

dissolving enzym, pepsin. The best evidence at hand 
at present rather favors the existence of two enzyms. 
For our purpose, it is immaterial whether there is one 
enzym or more. Our chief interest in rennet, in con- 
nection with the cheese-making process, lies in its 
characteristic property of coagulating milk-casein. 
Whether the dissolving action of rennet-enzym plays 
any part in the operation of cheese-making, we do 
not know at present. We do know, however, that it 
has some action in the cheese-ripening process (p. 
362). 

Source of rennet-enzym. — The rennet-extract 
used in cheese-making is a dilute and impure form ot 
rennet-enzym. The usual source of rennet-extract is 
the fourth stomach of a suckling calf. It is also pre- 
pared in more concentrated condition in the form of 
powders and of tablets. Enzyms having the same 
action as that of rennet are found also in plants and 
in other animals than calves. Some bacteria pro- 
duce a coagulating enzym like that in rennet. 

Home-made rennet-extract. — Formerly, cheese- 
makers purchased rennets from farmers and prepared 
the extract from time to time as needed. The stomach 
of a freshly slaughtered calf was cleaned, salted and 
dried by farmers and sold to the cheese-maker. In 
preparing the home-made extract, a number of ren- 
nets are cut in pieces and just covered with salt brine 
in a suitable vessel, about 3 or 4 pounds of salt 
being added to 100 pounds of water. The mix- 
ture is vigorously stirred and pounded. Once a week 
the rennets are removed from the brine and passed 
through a press or clothes-wringer and then placed 
in the brine again. It requires about four weeks to 



MICRO-ORGAN IS xMS AND ENZYMS 3OI 

complete the extraction. The solution thus obtained 
is filtered through clean straw, sand, and charcoal and 
then treated with enough salt to prevent decomposi- 
tion; a brine containing 6 or 7 pounds of salt to 100 
pounds of solution is about the proper strength. 
Rennet-extract properly prepared is dark in color, but 
clear. The appearance of turbidity in the extract is 
an indication of the beginning of decomposition. It 
must be kept in a cool, dark place. In some cases, 
whey was once used as a medium for preparing ren- 
net-extract, a practice that would insure a large num- 
ber of objectionable micro-organisms in the extract. 
It can readily be seen how home-made rennet-extract 
may be a source of serious bacterial contamination 
in milk. The preparation of home-made extracts is, 
fortunately, much less common now. The serious 
objections to their use are (i) liability to bacterial 
contamination and (2) variation in strength of dif- 
ferent lots, usually requiring the use of quite variable 
amounts of one preparation as compared with another. 

Commercial rennet-extract. — The general substi- 
tution of commercial for home-made rennet-extracts 
is of distinct advantage in cheese-making, because the 
commercial forms are much more uniform in strength 
and less liable to bacterial contamination. Commer- 
cial rennet-extracts contain about 16 per cent of salt 
and a trace of boric acid. Some have expressed the 
fear that the boric acid used as a preservative in ren- 
net-extract might injure the value of cheese as a pure 
food. There need be absolutely no alarm felt, when 
we consider the small amount of rennet-extract used 
in cheese-making and the very small proportion of 
this that goes into cheese. In fact, the amount of 



302 SCIENCE AND PRACTICE OF CHEESE-MAKING 

boric acid introduced into cheese through the rennet- 
extract is too small to identify by delicate chemical 
tests. Commercial rennet-extracts vary in strength 
and new lots always need testing before being used 
(P-430). 

Strength of rennet-enzym in coagulating milk- 
casein. — How powerful the action of rennet-enzym 
is in coagulating milk-casein can be seen in cheese- 
making, where we use only about one part of rennet- 
extract for 4,000 or 5,000 parts of milk, and it must 
be kept in mind that rennet-extract is only a dilute 
form of the rennet-enzym. It has been estimated that 
one part of pure rennet-enzym can coagulate three 
million parts of milk. Apparently, rennet-extract 
does not exhaust itself by its own action, a general 
characteristic of enzyms, but can be repeatedly used ; 
at least this is theoretically true. For example, if we 
could recover from whey and curd the rennet used 
in coagulating milk, it would coagulate an equal quan- 
tity again. As stated already, one of the most char- 
acteristic properties of an enzym is that it can produce 
very powerful effects without itself being affected in 
any way. 

Explanation of the coagulating action of rennet- 
enzym. — A large amount of effort has been devoted 
to the study of the coagulating effect of rennet-enzym 
in order to ascertain just what the rennet does to the 
milk-casein to make it coagulate. Many different ex- 
planations have been offered, but in the present state 
of our knowledge it is impossible to give an explana- 
tion of the process that can be regarded as satisfac- 
tory and conclusive. The most we can do here to 
advantage is to present the details of the process, so 



MICRO-ORGANISMS AND ENZYMS 303 

far as they appear to be worked out. The rennet 
coagulation of milk-casein is believed to take place 
in three quite distinct stages or phases, as follows : 
(i) "Change of casein into paracasein; (2) change 
of the calcium salts of the milk into soluble form ; 
and (3) precipitation of uncoagulated paracasein by 
the soluble calcium salts. 

(i) First stage of rennet action; change of casein 
into paracasein. — The change of casein into paracasein 
is wholly dependent on the action of rennet-enzym. 
There is no change visible to the eye, neither increase 
of consistency (viscosity) nor any apparent coagula- 
tion. In the absence of soluble calcium salts, the 
paracasein that has been formed remains in this un- 
coagulated condition. The action in this stage of the 
process takes place as well in the cold as at higher 
temperatures. What evidence have we that casein is 
changed into paracasein before coagulation takes 
place ? This is shown experimentally as follows : To 
a solution containing some salt of casein, free from 
soluble calcium salts, we add rennet-extract. No co- 
agulation takes place. This solution is heated high 
enough to destroy the power of the rennet to a.ct and 
then cooled, after which calcium chlorid or some other 
soluble calcium salt is added, when coagulation ap- 
pears at once. It may be stated here that one of the 
most characteristic differences between milk-casein 
and paracasein is that soluble calcium salts do* not 
coagulate milk-casein at ordinary temperatures, but 
they do cause coagulation of paracasein. In the fore- 
going experiment, rennet does something to the casein 
compound which causes the casein* to do what it could 
not do before, that is, coagulate at ordinary tem- 
peratures by addition of soluble calcium salts, even 



304 SCIENCE AND PRACTICE OE CllEESE-JMAKING 

when the rennet-enzym itself had been removed 
from the field of action. 

(2) Second stage of rennet action; change in 
calcium salts of milk. — In the second stage of rennet 
action, it is believed that the rennet-enzym acts upon 
the insoluble calcium salts of the milk, converting 
them into a form sufficiently soluble to enable them to 
coagulate the paracasein. This action appears to take 
place more slow^ly than does the conversion of casein 
into paracasein. This accounts for the period of time 
that elapses between addition of rennet and coagula- 
tion ; this time can be shortened by addition of soluble 
calcium salts. 

(3) Third stage of rennet action; precipitation of 
uncoagulated paracasein. — During this period, in- 
creased viscosity (thickening) and visible coagulation 
take place. This change, it is generally agreed, is 
caused by the action, either physical or chemical, of 
soluble calcium salts upon the uncoagulated paracasein 
formed during the first stage of the process. After 
the second stage is completed or nearly so, coagulation 
commences and proceeds rapidly. The paracasein 
coagulum (curd) formed in milk always contains in- 
soluble calcium phosphate, which is probably held in 
a purely mechanical way, although some believe that 
it is in combination with paracasein. 

What is the evidence leading us to believe that a 
soluble calcium salt is necessary for the coagulation of 
milk-casein ? Two lines of experimental evidence have 
been furnished, (ist) If we prepare a pure solution 
of neutral calcium casein or sodium casein, contain- 
ing no soluble calcium salts, rennet-extract will not 
coagulate such a solution, but, after the addition of 
some soluble calcium salt, as calcium chlorid. coagula- 
tion takes place promptly. (2nd) Milk from which 



MICRO-ORGANISMS AND ENZYMS 305 

the soluble calcium salts have been removed by pre- 
cipitation with ammonium oxalate or by dialysis is 
not coagulated by rennet-enzym until a soluble cal- 
cium salt is added. We may, therefore, summarize 
as follows what appears to be fairly well established 
in explanation of the coagulating action of rennet : 
(i) That milk-casein is the only substance in milk 
involved in the rennet coagulation, excepting phos- 
phates of calcium and other soluble salts of calcium. 
(2) That in rennet coagulation, no change of reaction 
or acidity occurs ; the milk becomes neither acid nor 
alkaline through rennet action. (3) That the two 
active agents in the rennet coagulation of milk are 
rennet-enzym and soluble calcium salts. 

Relation of casein and paracasein. — In the fore- 
going discussion of the process of rennet coagula- 
tion, there is nothing to indicate just what happens 
to milk-casein in being changed into paracasein, 
or, in other words, just how paracasein really dif- 
fers from milk-casein. It must be confessed that 
we do not know at all clearly, although there are 
many suggestions. We know only this with cer- 
tainty, that milk-casein does not readily coagulate 
in the presence of dilute calcium salts at ordinary 
temperatures, but paracasein does. Otherwise the 
general properties of casein and paracasein are 
very similar. Some hold that the difference is 
purely physical, the paracasein consisting of larger 
particles than the casein. While the ultramicro- 
scopic study (p. 143) of rennet coagulation enabled 
the observers to see the minute particles of casein 
come together and form larger aggregations under the 
action of rennet, this does not show whether this 



306 SCIENCE AND PRACTICE OF CHEESE-MAKING 

physical change was accompanied by any chemical 
change in the milk-casein. 

Dissolving or digesting action of rennet-enzym. — 

Rennet-extract has the power of dissolving paracasein, 
this peptic action being slow but continuing for a long 
time in cheese. Whether one enzym does both the 
coagulating and the digesting, or whether there are 
two specific enzyms (rennin and pepsin), each per- 
forming its special kind of work, is not fully settled, 
but, as already stated, the results of most recent in- 
vestigations point to two distinct enzyms. 

Conditions of action of rennet-enzym. — The con- 
ditions under which rennet-enzym coagulates milk- 
casein have been extensively studied and we will now 
consider some of the more important ones. The 
rapidity and completeness of coagulation of milk- 
casein by rennet-enzym are dependent upon the fol- 
lowing conditions : 

(i) The presence of soluble calcium salts appears 
to be necessary for the coagulation of milk-casein by 
rennet-enzym. This has been discussed already. 

(2) Effect of acids. — Milk must be neutral or acid 
in reaction in order to be coagulated by rennet-enzym. 
Free acids or acid salts favor the action. All acids, 
whether organic or inorganic, show very marked efifect 
upon the coagulation, though they diflfer from one 
another in respect to the extent of influence which 
they exert on rennet action. The more acid there is 
in the milk, up to a certain limit, the more quickly does 
coagulation by rennet-enzym take place. Milk sour 
enough to curdle is not coagulated by rennet; sim- 
ilarly, sour buttermHk is not coagulated. The follow- 
ing table shows the results of some work done at the 



MICRO-ORGANISMS AND ENZYMS 



307 



New York experiment station on this subject. The 
experiments were made by treating 350 cubic centi- 
meters of fresh milk at 84° F. with i.o cubic 
centimeter of rennet sohition, made by dissolving one 
of Hansen's rennet-tablets in 150 cubic centimeters of 
distilled water. 





Original 

milk 

coagulated 

in 

seconds 


Strength of acid used 


Acids used 


0.01 
per cent 


0.02 
per cent 


0.03 
per cent 


0.04 
per cent 


0.05 
per cent 




Time of coagulation in seconds 


Acetic 

Sulphuric 

Citric 


110 
105 
105 
110 
105 
135 


70 
70 
80 
80 
85 
110 


45 
50 
60 
65 
70 
90 


35 
30 
45 
45 
60 
80 


25 
25 
40 
35 
50 
75 


20 
20 

35 


Lactic 

Hydrochloric . 
Phosphoric . . 


30 
45 
60 



This effect of acids upon rennet action is com- 
monly explained by saying that the added acid dis- 
solves the insoluble calcium phosphates of milk and 
thus increases the amount of soluble calcium salts. 
It is known that even carbon dioxid gas favors rennet 
coagulation, due to its dissolving action on insoluble 
calcium salts in milk. 

(3) Dilution of milk by water both delays rennet 
action and renders coagulation less complete, because 
the proportion of soluble calcium salts is decreased. 
Addition of calcium chlorid or free acid to milk thus 
diluted not only hastens the time of coagulation, but 
makes more complete the amount of milk-casein co- 
agulated. Apparently, milk may be diluted more than 
10 per cent with water before the time of rennet 



308 SCIENCE AND PRACTICE OF CHEESE-MAKING 



coagulation is greatly affected. The effect of water 
is illustrated in the following table : 



Cubic 


Cubic centi- 


Percentage of 


Cubic centi- 




centimeters 


meters of 


added water 


meters of 


Time of 


of milk 


water added 


in watered 


rennet solu- 


coagulation 




to milk 


milk 


tion used 












Minutes-Secopds 


175 


175 


50 


0.5 


5 — 20 


175 


175 


50 


1.0 


3 — 20 


280 


70 


20 


1.0 


2 — 00 


315 


35 


10 


1.0 


1 — 50 


3321 


17i 


5 


1.0 


1 — 4S 


350 








1.0 


1 — 30 



(4) Different chemical compounds and metals 
affect the rennet coagulation of milk in different ways. 
Acid salts, in general, like free acids, favor rapidity 



of coagulation. 


Alkalis and 


alkaline salts retard it. 


The following 


substances, 


if present in certain 


amounts, retard 


rennet coagulation of milk-casein : 


Sodium chlorid 


(common 


salt), sodium acetate, 


borax, chloroform, formalin 


and some other sub- 




Origi- 


Strength of Compound Used 


Compound 


0.01 


0.05 


0.10 


0.5 


1.0 


2.0 


used 


nal 
milk 


per cent 


per cent 


per cent 


per cent 


per cent 


per cent 




Number of se 


conds required to coagulate milk 


Sodium chlorid 


110 


_ 




_ 


115 


120 


160 


Sodium nitrate 


— 


— 


— 


— 


— 


150 


225 


Sodium bicar- 
















bonate 


115 


115 


170 


265 


— 


— 


— 


Sodium acetate 


115 


120 


180 


280 


— 


— 


— 


Borax 


100 
100 


120 
100 


270 
100 


600 
90 


— 


— 





Boracic acid.. . 


— 


Ammonium 
















chlorid 


135 


140 


130 


130 


— 


— 


— 


Ammonium 
















carbonate ... 135 


150 


195 


300 


(lOcc.) 


(20rc.) 


(30cc.) 


Lime-water . . . 




— 


— 


— 


150 


165 210 



MICRO-ORGANISMS AND ENZYMS 309 

stances, which are used in milk as preservatives. TLc 
foregoing table shows the results of some work done 
at the New York experiment station on this point. 

It has been shown at the Wisconsin experiment 
station that some metals exert a retarding effect on the 
coagulating action of rennet. As a practical applica- 
tion, it is pointed out that in rusty milk-cans enough 
iron may be dissolved by milk that is at all acid to 
interfere with the rennet coagulation. 

(5) Finely divided, inert matter, like starch or 
sawdust, added to milk, hastens the coagulation by 
rennet. 

(6) The temperature of the milk affects (i) the 
time of coagulation, and (2) the character of the 
curd. 

(a) For complete coagulation, the time de- 
creases when the temperature increases. 



Temperature, F 75° 

Time, seconds 270 



80° 
140 



85° 
110 



90° 
80 



95° 
65 



Stated in another way, the coagulation in a given 
time is most complete at io6° to io8° F. and less 
complete at temperatures above and below these 
limits. Fleischmann gives the following figures, 
indicating the proportion of milk-casein coagulated in 
the same period of time required to effect complete 
coagulation at io6° to io8° F. 

Proportion of milk- 
Temperature casein coagulated 

68° 18 per cent 

77° 44 per cent 

86° 71 per cent 

95° 86 per ecnt 

104° 98 per cent 

106° * 100 per cent 

113° 89 per cent 

122° 50 per cent 



3IO SCIENCE AND PRACTICE OF CHEESE-MAKING 

(b) The character of the coagulation is af- 
fected by the temperature at which the rennet- 
enzym acts. Thus, at 60° F., the curd is flocculent, 
spongy and soft; at yy° to 113° F., it is more or less 
firm and solid; at 122° and above, it is very soft, loose 
and inclined to be gelatinous. 

(c) Alilk heated above 150° F. for a consider- 
able length of time coagulates less rapidly than nor- 
mal milk. The coagulum of such heated milk is 
highly flocculent, never a firm and solid mass, in the 
absence of soluble calcium salts or acids. Boiled 
milk fails to coagulate normally, if at all, by rennet- 
enzym, unless treated with some soluble calcium salt 
or some acid. The degree of heat used decreases the 
amount of soluble calcium salts in milk and also drives 
out any carbon dioxid present. 

(7) Exposure to sunlight weakens the coagulating 
power of rennet-extract. 

(8) Solutions of rennet-extract are affected by 
heat. — Rennet-extract heated for some time above 
140° F. becomes permanently weaker, or inactive. 
Rennet-enzym begins to suffer injury at about 120° F. 
Weak solutions are injuriously affected at tempera- 
tures as low as 105° F. Strong solutions are weak- 
ened by heating at 150° F. for 15 minutes, but are not 
entirely destroyed. High temperatures destroy the 
activity of rennet-enzym gradually, not instantane- 
ously. 

(9) Increase in amount of rennet-extract or in 
strength of rennet-enzym hastens coagulating effect on 
milk. 

(10) Milk, freshly draivn, curdles more com- 
pletely than when allowed to cool, due to lowering of 
temperature and, perhaps, to the presence of more 



MICRO-ORGANISMS AND ENZYMS 



311 



carbon dioxid. In freshly drawn milk, the proportion 
of casein coagulated decreases until the temperature of 
the surrounding air is reached, when it becomes sta- 
tionary, until the formation of lactic acid causes in- 
crease in activity of rennet-enzym. When fresh milk 
fails to coagulate with rennet-extract, it is probably 
slightly alkaline or contains no soluble calcium salts ; 
that is, it is abnormal. 

(11) Different milks behave differently toward 
rennet-enzym. This is true not only of milk from dif- 
ferent cows, but also of milk from the same cow at 
different times. The following results of work done 
at the New York experiment station illustrate this 
statement : 







Time 


of coagtilation and date of testing 








Number 
of cow 


July 9 


July 16 


July 21 


Aug. 10 


Aug. 21 


Sept. 15 


Sept. 25 


Oct 


. 30 


1 

2 
3 

4 


M.— S. 
6—15 
3—45 
2—15 
2—50 
2—10 
2-00 
2—05 
2-00 
4—15 
1—35 
1—35 
2—10 
1—05 

23—00 
0—50 
2—05 
1—55 


M.— S. 
5-00 
3—45 
2—50 
2—50 
2—15 
2-00 
1—55 
1—50 
4—20 
1—50 
1—35 
2—00 
1—10 

16—20 
0—45 
2—30 
1—45 


M,— S. 
5—20 
3—45 
2—50 
2—30 
2—05 
2-05 
2 — 00 
2—10 
3-00 
2—10 
1—35 
2—20 
1—10 

10-00 
0—50 
2-00 
1—55 


M.— S. 
4—20 
4—20 
3-00 
2—25 
2—05 
2—05 
2—05 
2—30 
2—40 
1—45 
1—35 
1—50 
1—10 

10-00 
0—45 
1—55 
2—05 


M.— S. 
6—45 
3—40 
2—45 
1—50 
2-00 
2—50 
1—55 
4—001 
3—30 
1—25 
1—35 
1—55 
1—05 

29-00 
1—00 
3-00 
1—40 


M.— S. 
8—30 
3—30 
2-00 
3—30 
1—25 
2—45 
1—50 

3—66 
1—40 
1—35 
1—45 
1—05 
4—45 
0—50 
3—00 
1—35 


M.- 
7- 
5- 
2- 


-S. 
-00 
-00 
-00 


M.- 
6- 
4- 
2- 


-S. 
-00 

-15 
-00 


5 
6 
7 
8 


2- 
2- 
1- 


-00 
-40 
-55 


2- 
2- 
1- 
3- 
2- 


-30 
-15 
-402 
-10 


9 
10 


3- 
1- 
1- 
2- 
1- 
50- 
0- 
3- 
1- 


-45 
-45 
-40 
-30 
-10 
-00 
-40 
-10 
-40 


-00 


11 




12 




13 




14 
15 
16 


7—00 
0—45 


17 


1- 


-30 



1 Close of lactation period. 2Fresh in milk. 



These results show that in the individual milkings 
of these 17 cows the time of rennet coagulation of 
fresh milk varied from 40 seconds to 50 minutes. In 



312 SCIENCE AND PRACTICE OF CHEESE-MAKING 

the case of one individual (No. 14), the variations 
were from 4 minutes and 45 seconds to 50 minutes. 
A study of the ordinary composition of the milk gave 
no clue to the cause of such differences. The specific 
causes are not yet understood, but are probably related 
to the calcium salts in milk and their solubility. 

PEPSIN-ENZYM 

The chief enzym of the gastric juice in the stomach 
of man is known as pepsin. The same enzym is also 
present in the stomach of many animals. A prepara- 
tion made from the stomachs of sheep is on the 
market, which may be successfully used as a sub- 
stitute for rennet-extract in cheese-making. This 
has the property of both coagulating and digesting 
milk-casein. The pepsin most experimented with 
has been the scale pepsin of Armour & Co. This 
pepsin does not coagulate very sweet milk as read- 
ily as rennet-extract, but in milk having an acidity 
of 0.20 per cent, it acts just as well, when used in 
the proportion of 5 grams for 1,000 pounds of 
milk. The pepsin is dissolved in any convenient 
amount of water before addition to milk. The 
solution should be prepared fresh for each day's use. 
The complete identity of rennet-enzym and pepsin is 
not fully settled. Assuming that the coagulating 
effect of these preparations is due to one enzym 
(rennin) and the digesting effect to another (pepsin), 
the various preparations differ in respect to the 
amounts of these two enzyms which they contain. 
Rennet-extracts contain more rennin and less pepsin, 
while the commercial preparations made from the 
stomachs of pigs and sheep appear to contain more 
pepsin and less rennin. 



CHAPTER XXIII 

The Ripening of Cheese 

It is well known that cheddar cheese must have age 
before it is edible. When taken from the press, cheese 
is said to be unripe, green, or uncured. At this time, 
it has no real cheese flavor, and little flavor of any 
kind. Its body is very firm, somewhat tough, rather 
elastic, and rubber-like. Its proteins are only slightly 
soluble in water. It is not palatable and requires much 
mastication before it can be swallowed comfortably. 
Green cheese gradually undergoes very marked 
changes in the course of some weeks or months, the 
time required depending upon a variety of conditions. 
The cheese finally becomes mellow in body and ac- 
quires richness of taste and a characteristic delicacy of 
flavor. It is highly palatable and, when a piece is 
held on the tongue a short time, the cheese dissolves, 
giving a sensation of smoothness and richness. The 
casein-derived proteins, which are insoluble as found 
in the curd and green cheese, become soluble to a 
large extent. The process, by which the. qualities of 
the newly made cheese are so profoundly changed 
and as a result of which the product becomes edible, 
is known as ripening or, less aptly, as curing. 

For a long time the importance of caring for cheese 
after it leaves the press was not appreciated, and not 
until within about 15 years has much attention been 
given to methods of cheese-ripening in this country. 
The rule has been and still is, in too many cases, to 

313 



314 SCIENCE AND PRACTICE OF CHEESE-MAKING 

place the cheese in some room in the factory where 
are provided no means of controlhng temperature and 
moisture and where the variations in these factors 
closely follow, up and down, the conditions existing 
out of doors. It has come to be realized that a cheese, 
perfect when it leaves the press, may easily be ruined 
for market by lack of care during the ripening process. 
It is appreciated now more than ever before that the 
ripening of cheese is a part of the manufacturing proc- 
ess, that it is the real finishing of the product, and 
must not be slighted any more than any other impor- 
tant step. 

CHANGES RESULTING FROM RIPENING 

PROCESS 

Several different changes take place in cheese dur- 
ing the ripening period. These may be divided into 
two general classes, (i) loss of weight anS (2) 
chemical changes in the cheese constituents. We 
shall now take up for consideration a somewhat de- 
tailed study of (i) the extent to which these 
changes take place, (2) the various conditions under 
which they occur, (3) their relations to the character 
of the cheese and (4) the commercial relations of 
cheese-ripening. 

LOSS OF WEIGHT IN CHEESE-RIPENING 

The loss of weight in the cheese-ripening process, 
when the conditions are normal, may be regarded for 
practical purposes as being due entirely to the evapora- 
tion of water from the cheese. Of course, there is 
some mechanical loss of fat by exudation ("leaking") 
from cheese kept at high temperatures, but such con- 
ditions are abnormal. The small amount of loss due 



RIPENING OF CHEESE 315 

to the formation and escape of carbon dioxid (p. 
334) and other gases can be neglected for practical 
purposes. 

CONDITIONS AFFECTING LOSS OF WATER 
IN CHEESE-RIPENING 

The rapidity and extent of loss of moisture in 
cheese during the process of ripening vary with sev- 
eral conditions, chief of which are the following: (i) 
The temperature of the room, (2) the proportion of 
water- vapor present in the air of the room, (3) protec- 
tion of surface of cheese, (4) size and shape of the 
cheese, (5) the percentage of moisture originally pres- 
ent in the cheese, and (6) the texture of the cheese. 
The data used in illustrating these points are taken 
largely from the results of investigations carried on 
at the New York experiment station. 

Temperature and loss of weight. — We present, 
first, data showing the influence of temperature upon 
the loss of moisture at six different temperatures, viz : 
55°, 60°, 65°, 70°, 75° and 80° F. 

The cheeses used in furnishing data in the table on 
page 316 were 15 inches in diameter and weighed 
about 65 pounds, the usual standard size of the most 
common type of American cheddar cheese intended 
for export trade. 

These results show an increase in loss of weight 
with increase of temperature. As between 55° and 
80° F., the loss increased on an average i ounce per 
100 pounds of cheese for each additional degree of 
temperature during the first 4 weeks ; 2 ounces per 
100 pounds of cheese for each degree during the first 
2 months ; and 3^ ounces at the end of 3 months. 



3l6 SCIENCE AND PRACTICE OF CHEESE-MAKING 



LOSS OF MOISTURE AT DIFFERENT TEMPERATURES 



Tempera- 
ture of 
curing- 
room 



Water lost by 100 pounds of green cheese in 



1 

wk. 



2 
wks. 



3 
wks. 



4 
wks. 



8 


12 


16 


20 


24 


wks. 


wks. 


wks. 


wks. 


wks. 


Lbs. 


Lbs. 


Lbs. 


Lbs. 


Lbs. 


5.2 


6.1 


6.8 


7.5 


8.1 


5.5 


6.5 


7.5 


8.5 


9.3 


5.8 


7.0 


8.2 


9.2 


10.1 


6.0 


7.8 


9.0 


10.1 


11.1 


7.2 


9.7 


11.4 






8.3 


11.6 


15.5 







28 
wks. 



Degrees F. 
55 
60 
65 
70 
75 
80 



^bs. 


Lbs. 


Lbs. 


Lbs. 


1.6 


2.6 


3.2 


3.7 


1.7 


2.8 


3.4 


3.9 


1.9 


3.0 


3.6 


4.1 


2.0 


3.1 


3.7 


4.3 


2.2 


3.3 


4.0 


4.7 


2.4 


3.7 


4.5 


5.2 



Lbs. 

8.6 

9.9 

10.5 

12.0 



The average weekly loss of weight increases with 
increase of temperature. In the following table, it 
is seen that the loss is greater the first week than in 
any succeeding week. The loss usually decreases 
gradually as the cheese grows older ; but cheese kept 
at a temperature of 75° F. and above does not follov\^ 
this general rule, since at the higher temperatures 
there is apt to be an increase of loss of weight due to 
leakage of fat after the first month. This is shown 
in the table below : 



AVERAGE WEEKLY LOSS AT DIFFERENT TEMPERATURES 







Average loss per week. 








Temper- 




Water lost by 100 pounds of green 


cheese. 


Ibs.total 


ature f)f 










loss for 


curing- 




















six 


room 


1st 


2d 


3d 


4th 


2d 


3d 


4th 


5th 


6th 


months 




wk. 


wk. 


wk. 


wk. 


mo. 


mo. 


mo. 


mo. 


mo. 




Deg. F. 


Ozs. 


Ozs. 


Ozs. 


Ozs. 


Ozs. 


Ozs. 


Ozs. 


Ozs. 


Ozs. 


Lbs. 


55 


25.6 


16.0 


9.6 


8.0 


6.0 


3.6 


2.8 


2.8 


2.4 


8.1 


60 


27.2 


17.6 


9.6 


8.0 


6.4 


4.0 


4.0 


4.0 


3.2 


9.3 


65 


30.4 


17.6 


9.6 


8.0 


6.8 


4.8 


4.8 


4.0 


3.6 


10.1 


70 


32.0 


17.6 


9.6 


9.6 


6.8 


4.8 


4.8 


4.4 


4.0 


11.1 


75 


35.2 


17.6 


10.2 


10.2 


10.0 


10.0 


6.8 








80 


38.4 


20.8 


12.8 


10.2 


12.4 


13.2 


15.6 









RIPENING OF CHEESE 



317 



The comparatively rapid loss of moisture during 
the early stage of ripening iS" due to the fact that the 
cheese contains its highest amount of moisture when 
new. In addition, the bandage is practically saturated 
with water, which quickly evaporates. Then, again, 
the outer surface of the cheese, in drying, begins to 
harden, the meshes of the cheese-cloth filling to some 
extent with dried matter, and this condition tends con- 
stantly more and more to diminish evaporation, pro- 
vided cracking is prevented. 

Moisture in air of curing-room and loss o£ 
weight. — The relative amount of moisture in air or, 
more properly, the degree of saturation, exercises 
a marked influence upon loss of water in cheese-ripen- 
ing. To illustrate this influence, we give results of 
an experiment in which two cheeses made from the 
same milk were kept at 60° F. One cheese was kept 
on a shelf in the ordinary manner, the air of the 
room containing from 75 to 80 per cent of all the 
moisture it could hold at 60° F. The other cheese 



LOSS OF MOISTURE IN CHEESE KEPT IN AIR COM- 
PLETELY AND PARTIALLY SATURATED WITH MOISTURE 



Age of 


In air partially saturated 


In air completely satu- 
rated with moisture 


cheese 


Moisture in 
cheese 


Wateriest by 

100 pounds of 

cheese 


Moistiire in 
cheese 


Water gained 

by 100 poimds 

of cheese 


2 weeks. . . . 

1 month . . . 

2 months. . 
6 months. . 

11' months. . 
15 months. . 


Per cent 
35.99 
35.23 
34.86 
31.87 
26.30 
24.85 


Pounds 


Per cent 
35.93 
35.87 
36.01 
. 37.04 
37.63 
37.85 


Pounds 


0.76 
1.13 
4.12 
9.69 
11.14 




0.08 
0.11 
1.70 
1.92 



3l8 SCIENCE AND PRACTICE OF CHEESE-MAKING 



was placed under a bell- jar and kept in an atmosphere 
completely saturated with moisture. The results 
secured by this treatment are presented in the table 
on the preceding page. 

The results of this experiment are quite striking. 
In the cheese kept in air incompletely saturated with 
moisture, there wa-s a steady loss, so that the cheese 
which contained 36 per cent of moisture at the start 
had its moisture content decreased to less than 25 
per cent. On the other hand, the cheese kept in a 
sa-turated atmosphere not only lost no moisture, but 
actually gained water by absorption, so that its per- 
centage of water was increased from about 36 per 
cent at the beginning to nearly 38 per cent at the 
close of the experiment. The two cheeses, which 
contained the same percentage of moisture at the 
beginning, were found to differ, at the end of 15 
months, 13 per cent in moisture, solely as the result 
of being kept in air containing different degrees of 
moisture. 

The same fact is well illustrated in experiments 
made at the Wisconsin experiment station. A com- 
parison was made of the relative humidity of the air 
in a curing-room with that inside a closed cheese- 
box, in which a cheese was kept. 





Temperature 


Relative^ 

humidity in 

room 


Relative 

humidity inside 

cheese-box 


Room 1 

Room 2 

Room 3 


350.40° F. 
50°-55°F. 
60°-69° F. 


Per cent 
85-92 
55-75 
50-70 


Per cent 
100 
94 
84-90 



RIPENING OF CHEESE 3I9 

These results indicate that the storage of cheese in 
boxes in curing-rooms is one means of avoiding the 
results of too rapid loss of nrois'ture. Of course, dif- 
ficulty arises in the way of molds in the case of cheese 
so stored, unless they are properly fumigated (p. 
134) or covered with paraffin, a point which will be 
considered next. 

Protection of surface of cheese and loss of 
weight. — The covering of the outer surface of 
cheese with a layer of paraffin has been fourKl to 
diminish greatly the loss of weight. The first sugges- 
tion of the practical use of paraffin in connection 
with covering cheese came, so far as we know, from 
the Standard Oil Company about lo or 12 years 
ago, when it advertised a preparation of yellow- 
colored paraffin for use in protecting cheese from 
mold. Some experiments were made at the Wis- 
consin experiment station in 1899 to prevent mold 
by the use of paraffin, but the- results were not re- 
garded as sufficiently satisfactory in every way to 
justify its recommendation for general use. In ex- 
perimental work at the New York experiment 
station, cheese was covered * with paraffin in order 
to control moisture, without any reference to the 
thought of practical application. The matter was 
later taken up in a practical way here and in Can- 
ada. The results of co-operative work between 
the United States Department of Agriculture and the 
experiment stations of Wisconsin and New York, 
carried on in 1902-3, may be regarded as the first 
demonstration in the United States that attracted 
serious attention. Since then the practice has grown 



320 SCIENCE AND PRACTICE OF CHEESE-MAKING 

rapidly, but the primary object is quite as much pre- 
vention of loss of weight as protection from mold. 
The results of the work done at that time in New 
York will suffice as a basis of discussion. Cheeses 
weighing 70 pounds were used, some being covered 
with paraffin, while others were left in the usual con- 
dition. The results are given as follows : 





Age 


Pounds lost for 100 pounds of cheese 


Cheese 










Kept at Kept at 


Kept at 






40°F. 


50°F. 


60°F. 




Weeks 








Normal 


17 


2.5 


2.4 


4.2 


Paraffined 


17 


0.3 


0.5 


1.4 


Normal 


25 


3.1 


4.0 


— 


Paraffined 


25 


0.6 


0.9 


— 


Normal 


32 


4.5 


— 


— 


Paraffined 


32 


0.9 


" — ■ 


— 



By covering cheese with paraffin, a saving in loss 
of moisture can be effected, amounting to 5 or 6 
pounds per 100 pounds of cheese at 60° F. ; while at 
50° F., and below, the total loss of moisture can be 
reduced to less than i pound per 100 pounds of cheese. 
In every case, cheeses covered with paraffin were 
entirely clean, while the others were more or less 
heavily coated with molds. The saving effected by 
paraffining small-sized cheeses is even greater than 
with those of larger size. 

Size and shape of cheese in relation to loss of 
weight. — The amount of external surface is greater 
in relation to weight in the case of a small cheese than 
of a larger cheese, and we should, therefore, expect 
a larger loss of moisture. 



RIPENING OF CHEESE 



321 



The following- table illustrates the losses of weight 
in the case of cheeses 7 inches in diameter; this is 
the type commonly known as ''Young America." 
They were made from one vat of milk and kept 
at 65° F. 

WEIGHT LOST BY CHEESES OF VARYING HEIGHT AND 
UNIFORM DIAMETER 





' 




Water lost by 100 pounds 


of green cheese in 




Height 


Weight 
of 












of 




















cheese 


green 


1 


2 


3 


4 


8 


12 


16 


20 


24 




cheese 


wk. 


wks. 


wks. 


wks. 


wks. 


wks. 


wks. 


wks. 


wks. 


Inches 


Pounds 


Lbs. 


Lbs. 


Lbs. 


Lbs. 


Lbs. 


Lbs. 


Lbs. 


Lbs. 


Lbs. 


,3 


4.6 


3.4 


5.3 


6.4 


7.0 


10.7 


12.9 


13.9 


15.9 


17.0 


4 


6.1 


3.3 


5.1 


6.1 


6.7 


9.7 


11.5 


13.0 


14.0 


15.6 


5 


7.9 


2.8 


4.2 


5.5 


6.3 


8.3 


9.8 


11.2 


12.6 


13.4 


6 


9.3 


2.5 


3.9 


5.2 


60 


7.8 


9.4 


10.6 


11.6 


12.8 


7 


11.0 


2.3 


3.4 


4.7 


5.6 


7.4 


8.9 


10.5 


11.2 


12.4 



The loss of weight decreases with increase in height. 
Taking the total loss of weight for different periods 
of time, it is seen that an increase of one inch in height 
reduced the loss of weight per loo pounds of cheese 5 
ounces at the end of 4 weeks, 13 ounces at 8 weeks, 
16 ounces at 12 weeks and 18 ounces at 20 weeks. 

In the table on the next page we show the loss of 
weight in the case of cheeses having different diameters 
and kept at temperatures ranging from 55° to 80° F. 
It is seen that, in general, the loss of weight increases 
at all temperatures as the diameter increases, the dif- 
ference being greater at higher temperatures. 

Variation of loss of moisture w^ith different kinds 
of cheese. — In making small cheeses like "Young 
Americas," and smaller sizes (p. 44) the propor- 
tion of loss is much greater, and hence the demand 



2^2.2 SCIENCE AND PRACTICE OF CHEESE-MAKING 



WEIGHT LOST BY CHEESES OF VARYING DIAMETER AND 
UNIFORM HEIGHT 







Tem- 




Water lost by 100 pounds of cheese 






Weight 
of 


pera- 
ture 














Diam- 


















eter of 


green 


of 


1 


2 


4 


8 


12 


16 


20 


24 


cheese 


cheese 


curing- 
rooms 


\vk. 


wks. 


wks. 


wks. 


wks. 


wks. 


wks. 


wks. 


Inches 


Lbs. 


Deg.P. 


Lbs. 


Lbs. 


Lbs. 


Lbs. 


Lbs. Lbs. 


Lbs. 


Lbs. 


15 


65 


80 


2.4 


3.7 


5.2 


8.3 


11.6 ' 15.5 


' 




7 


9 


80 


3.6 


5.2 


7.3 


10.9 


12.7 ; 14.5 


16.3 


iV.i 


15 


65 


75 


2.2 


3.3 


4.7 


7.2 


9.7 11.4 






7 


9 


75 


3.1 


4.8 


6.6 


9.2 


11.1 12.7 


14. i 


is'.i 


IS 


65 


70 


2.0 


3.1 


4.3 


6.0 


7.8 9.0 


10.1 


11.1 


11 


23 


70 


3.0 


4.2 


6.1 


7.7 


9.2 


10.6 


11.6 


12.4 


7 


9 


70 


2.9 


4.5 


6.2 


8.9 


10.9 


12.2 


13.9 


14.6 


IS 


65 


65 


1.9 


3.0 


4.1 


5.8 


7.0 


8.2 


9.2 


10.1 


13 


31 


65 


2.0 


3.4 


5.1 


6.2 


7.7 


8.7 


9.3 


10.2 


11 


22 


65 


2.6 


3.7 


5.3 


6.9 


8.1 


9.5 


10.4 


11.3 


7 


9 


65 


2.5 


3.9 


5.6 


7.9 


9.5 


10.9 


12.1 


13.1 


15 


65 


60 


1.7 


2.8 


3.9 


5.5 


6.5 


7.5 


8.5 


9.3 


13 


31 


60 


1.7 


2.7 


4.3 


6.1 


7.3 


8.4 


9.5 




11 


22 


60 


1.9 


3.6 


4.5 


6.3 


7.5 


8.7 


9.6 


10.5 


7 


9 


60 


2.4 


3.7 


5.5 


7.7 


9.3 


10.6 


11.9 


12.8 


15 


65 


55 


1.6 


2.6 


3.7 


5.2 


6.1 


6.8 


7.5 


8.1 


13 


29 


55 


1.5 


2.7 


4.2 


5.7 


7.2 


7.9 


8.9 


9.4 


11 


20 


55 


2.1 


3.6 


4.6 


6.4 


7.4 


8.8 


9.4 


10.1 


7 


9 


55 


2.2 


3.6 


5.1 


7.2 


8.8 


9.8 


11.0 


12.0 



is still more imperative that these shall be cured 
under conditions where the loss of moisture shall 
be greatly reduced. This applies also to such 
sizes as ''Flats" and "Twins." It is not surprising 
that the manufacture of small cheeses of the Ched- 
dar type has been discouraged. Even at the 
higher prices they bring, the extra loss of moisture 
and additional cost of manufacture are not satisfac- 
torily covered. Tn the manufacture of small, fancy 
kinds of soft cheese, these statements do not apply, 
because an essential part of the equipment consists of 



RIPENING OF CHEESE 



323 



curing-cellars of fairly low temperature and high 
moisture content. 

Percentage of moisture in cheese and loss of 
weight. — Below are given results obtained with 
cheese made so as to contain water varying from 35 
to 55 per cent when taken from press. 

LOSS OF MOISTURE IN CHEESES CONTAINING DIFFERENT 
PERCENTAGES OF WATER 



Water in 100 


Water lost by 100 pounds of green cheese 


pounds of green 
cheese 


In 1 week 


In 2 weeks 


In 3 weeks 


In 4 weeks 


Pounds 
55 
50 
45 
35 


Pounds 
9.0 
5.5 
4.5 
3.3 


Pounds 

11.2 

9.2 

6.3 

4.2 


Pounds 

12.3 

11.0 

8.0 

4.9 


Pounds 

16.8 

12.9 

9.5 

5.7 



These results show that the more moist a cheese 
is when made, the greater is the proportion of water 
lost by evaporation ; and, hence, the moisture in the 
different cheeses tends to become more nearly alike 
than at the start. Thus, cheese containing 55 per 
cent of moisture lost about three times as much weight 
as did the cheese containing 35 per cent of water and 
nearly twice as much as the one with 45 per cent. 
Even when cheeses do not differ so widely in water 
content as those above, the same general rule holds 
good, Other conditions, of course, being the same. 



Pounds of water in 100 pounds of green cheese . 
Pounds of water lost by 100 pounds of green 
cheese in 6 weeks 



41.7 
5.3 



4.6 



37.6 
4.S 



35.4 
4.2 



324 SCIENCE AND PRACTICE OF CHEESE-MAKING 

Texture of cheese and loss of moisture. — Cheese 

filled with holes will occupy more volume than the 
same weight of cheese free from holes. Hence, cheese 
with such faulty texture has a larger surface exposed 
for evaporation relative to its weight and will lose 

RIPENED AT 40°F 





lit^-f.»afy,a;i; fJ.l l )»l j ^»^ i ^.^^^_._^^ . ,g^,.,^^ 




RIPENED AT 60^F 

FIG. 45 — SECTIONS OF TWO CHEESES RIPENED AT DIFFERENT 
TEMPERATURES. CLOSE-TEXTURED, CHEDDAR TYPE 



more moisture. Then, in addition, the presence of 
numerous holes in cheese greatly facilitates the escape 
of moisture from the interior of the cheese to the sur- 
face. This is a partial explanation of the fact that 
cheese high in moisture loses water more rapidly 



RIPENING OF CHEESE 



325 



than cheese containing less moisture. It is well 
known that cheese containing high percentages of 
water usually develops holes abundantly, especially 
when cured at or above ordinary temperatures. 

These statements are effectively illustrated in the 
experiments carried on at the Wisconsin experiment 
station; results are given for two distinct types of 
cheese, which were used in studying the effects of 
temperature during ripening: (i) Close-textured, 

RIPENED AT 40°F 




RIPENED AT 60°F 

FIG. 46 — SECTIONS OF TWO CHEESES RIPENED AT DIFFERENT 
TEMPERATURES. SWEET-CURD TYPE 



^26 SCIENCE AND PRACTICE OF CHEESE-MAKING 



firm-bodied, long-keeping type, suitable for export 
trade, typical Wisconsin cheddars. (2) Sweet-curd 
type, as represented by Iowa and Illinois methods of 
manufacture. In connection with the table below, 
study Figs. 45 and 46. 

The followmg table gives the results in loss of 
moisture in the cases of these two types of cheese : 



LOSS OF MOISTURE 





Type 1 


Tvpe 2 


Tvpe 1 


Tvpe 2 


Age 


(cheddar) 


(sweet-ctird) 


(cheddar) 


(sweet-curd) 


when 










ex- 










amined 


27 cheeses 


9 cheeses 


9 cheeses 


5 cheeses 




kept at 40°F. 


kept at 40°F. 


kept at 60°F. 


kept at 60°F. 


Days 


Per cent 


Per cent 


Per cent 


Per cent 


10 


0.38 


0.69 


0.96 


1.05 


20 


0.44 


0.82 


1.74 


1.77 


30 


0.58 


0.96 


2.05 


2.29 


60 


0.83 


1.15 


2.95 


3.67 


90 


1.00 


1.42 


3.57 


4.47 



CHAPTER XXIV 

Chemical Changes m Cheese Ripening 

In studying the chemical changes which take place 
during the process of cheese-ripening, it will be an 
advantage to consider the subject under the following 
main lines of inquiry : 

1. What chemical compounds are found in unripe 
cheese ? 

2. What chemical changes do the compounds of 
unripe cheese undergo as cheese ripens? 

3. What conditions influence the character and 
extent of these chemical changes? 

4. What causes the chemical changes of cheese- 
ripening? 

The first three points will be considered in this 
chapter, the fourth being reserved for a separate 
chapter. 

CHEMICAL COMPOUNDS IN UNRIPE 
CHEDDAR CHEESE 

Stanting with unripe cheese as it comes from the 
press, we find the same chemical compounds and 
groups of compounds mentioned in connection with 
the composition of milk, viz: (i) Water, (2) pro- 
teins, (3) fat, (4) sugar, (5) neutral and acid 
salts, (6) salt and (7) gases. 

Water. — The functions, amounts and ripening 
losses of water in relation to cheese have already 

327 



^2S SCIENCE AND PRACTICE OF CHEESE-MAKING 

been considered. We shall later consider its rela- 
tion to the chemical changes in cheese-ripening. 

Proteins.— In cheddar cheese fresh from press, 
there appear to be different protein compounds, the 
precise nature of which has not yet been deter- 
mined. There have been shown to be the follow- 
ing forms: (i) Protein soluble in warm (122°- 
131° F.), 5 per cent solution of sodium chlorid, 
which, for convenience, we shall speak of as brine- 
soluble protein, (2) protein insoluble in brine solu- 
tion, and (3) proteins soluble in water. The first 
constitutes the largest amount, often being 75 to 
90 per cent of the total amount of proteins in ched- 
dar cheese; the water-soluble protein is quite fairly 
constant, varying usually between 4 and 5 per cent 
of the total proteins, and a part of this is readily 
accounted for by the milk-albumin in the whey re- 
tained in the cheese. 

Fat. — The fat present in unripe cheese is, in 
composition and physical condition, essentially 
milk-fat. 

Milk-sugar. — The sugar in newly made cheese is 
simply milk-sugar in solution in the whey that is 
retained by the cheese. 

Neutral salts and acid salts. — The most promi- 
nent neutral salt in unripe cheese is calcium lactate, 
formed as a result of the lactic acid (produced by 
the fermentation of milk-sugar) upon the insoluble 
calcium phosphate originally present in the milk, most 
of which is carried into the cheese-curd and held 
there. The soluble acid salts present in largest 
amounts are calcium acid phosphate and, probably, 
citrate. 



I 



CHEMICAL CHANGES IN RIPENING 329 

Salt. — The unripe cheese contains common salt 
which has been added to the curd in the operation 
of cheese-making. This is held in solution, really 
constituting a weak brine containing about 3 per cent 
of salt. 

Gases. — In normal, unripe cheese, gaseous prod- 
ucts, except carbon dioxid, are present in only 
minute amounts, if at all. In cheese made from 
milk containing abnormal micro-organisms, there 
may be present such gases as hydrogen, carbon di- 
oxid, etc. 

CHEMICAL CHANGES IN COMPOUNDS OF 
UNRIPE CHEESE 

We will now take up each division of the com- 
pounds which we have considered briefly in the pre- 
ceding section and notice some of the changes which 
they undergo. 

Water. — So far as we know, the water in cheese 
undergoes no chemical change. It gradually 
evaporates from the cheese in the form of water- 
vapor, the rate of evaporation varying with condi- 
tions studied in the preceding chapter. 

Proteins. — Of all the compounds contained in 
unripe cheese, the proteins are the ones that are 
most extensively affected by the chemical changes 
of ripening, because these compounds are not only 
the seat of those changes but the material itself 
which iindergoes chemical changes more profound 
and complex than any other constituent of the 
cheese. There have been and still are many diffi- 
culties in carrying on a study of the chemical 



330 SCIENCE AND PRACTICE OF CHEESE-MAKING 

changes in cheese proteins during ripening, owing 
largely ( i ) to a lack of detailed knowledge of the 
compounds formed and (2) to need of more perfect 
methods for estimating the amounts of these com- 
pounds, many of which are formed only in very small 
quantities. 

Beginning with the milk-casein in the cheese-vat 
at the time the rennet is added, we have, from that 
time on, a succession of changes in the curd and 
cheese, resulting sooner or later in the formation of 
a series of compounds, which, so far as -our present 
knowledge goes, appears in something like the fol- 
lowing consecutive order: 

(1) Calcium paracasein (formed from the cal- 
cium casein of milk by action of rennet). In- 
soluble in water and in warm, 5 per -cent salt-brine. 

(2) Protein soluble in warm, 5 per cent salt-brine. 
(Figs. 30 and 31, p. 148.) 

(3) Protein insoluble in salt-brine, water, etc. 

(4) Proteins soluble in water: 

(a) A protein which is precipitable by dilute 
hydrochloric acid, called paranuclein. 

(b) A protein substance -coagulated in neutral 
solution at the boiling- point of water. This sub- 
stance appears to occur only rarely, except in the case 
of cheese ripened near freezing point. 

(c) Proteoses or caseoses (albumoses), which 
are proteins or pfrotein derivatives soluble in water, 
not coagulated by heat, and usually precipitated by 
saturating their solutions with zinc sulphate or am- 
monium sulphate. 

(d) Peptones, protein derivatives simpler than 
the proteoses, soluble in water, not coagulated by 



CHEMICAL CHANGES IN RIPENING 33I 

heat, and not precipitated by saturation with zinc 
sulphate or ammonium sulphate ; precipitated by 
phosphotungstic acid, tannic acid and some other 
reagents. 

(e) Amino acids, the simplest protein deriva- 
tives (except ammonia). 

(f) Ammonia. 

It would be beyond the scope of this book to go 
further into the details of the chemistry of these 
compounds, since they are very complex and require 
a special knowledge of organic chemistry to under- 
stand. 

The amounts of these protein-derived products vary 
with many conditions, some of which will be con- 
sidered later (p. ^Tfy). 

Fat. — There have been numerous investigations 
made by different workers to ascertain whether the 
milk-fat in cheese decomposes during the ripening 
process. The general results of these investiga- 
tions show that cheese-fat is unchanged milk-fat and 
that these glycerin-acid compounds (glycerids) (p. 
140) do not share extensively in the ripening proc- 
ess, especially in the case of hard cheese, such as 
cheddar. In one case, it was found that from i.o 
to 7 per cent of the cheese-fat had undergone some 
decomposition, the higher amounts occurring in 
soft cheese. One of the early investigators (Blon- 
deau) made several analyses of Roquefort cheese 
at various ages and reported that the proteins of 
the unripe cheese changed rapidly into fat. This 
statement, though frequently disproved later, has 
not even yet entirely disappeared from physiologi- 
cal literature. The conclusions were based upon 



'>^2i2 SCIENCE AND PRACTICE OF CHEESE-MAKING 

evident errors of analysis, which are readily appar- 
ent on careful examination. More recent work, 
however, claims that some organisms can change 
casein into fatty acids, while this is especially 
denied by another investigator. So far as we now 
know, the matter appears to be one mainly of 
academic interest, since the change must be insig- 
nificant in amount, if it occurs at all. In all of 
our extended work with cheese, we have found no 
evidence of an increase of fat at the expense of 
proteins. And no one has yet reported an accumu- 
lation of fat in a separator skim-milk cheese during 
the ripening process, where the conditions surely 
furnish enough protein material for such a trans- 
formation. 

There is, however, one interesting condition 
under which some fat appears to be changed, and 
that is in case of cheese cured at low temperatures, 
when we should ordinarily least expect such 
change. It has been observed that, in cheese cured 
near the freezing point of water, small white specks 
may appear. These have been noticed at both the 
Wisconsin and New York experiment stations as 
well as in Europe. They have been supposed by 
some to be salts of the cheese crystallized out In 
little white aggregations, due to the dryness of the 
cheese and the low temperature. One investiga- 
tor has reported the spots as due to the result of 
bacterial action on the fat in cheese, some of which 
was decomposed, the decomposed portions forming 
the minute white spots. Recently some cheese 
filled with these white specks has been examined 
at the New York experiment station; The white 



CHEMICAL CHANGES IN RIPENING 333 

Spots are about one-eighth the size of an ordinary 
pin-head. They are more or less completely dis- 
tributed through the mass of the cheese, appearing, 
perhaps, more numerous or, at least, more promi- 
nent in the lines where the pieces of curd are 
cemented together. Wherever there is a mechani- 
cal-hole, its walls are well covered and here the 
specks appear specially prominent because they 
simply lie on the walls and are not imbedded in 
the body of the cheese. They can be easily de- 
tached. When examined under a magnifying glass, 
the sniall specks appear glistening white and also, 
in some cases, the edges of the curd pieces, where 
they are cemented together, have the same appear- 
ance, very closely resembling paraffin. The specks 
crush easily, like fat. An examination showed them 
to contain calcium, but no phosphoric acid or other 
inorganic salt in appreciable amounts. Besides 
calcium, tliere appears to be some fatty acid, so 
that the substance appears to be a calcium soap. 
Some of the fat in the cheese is probably decom- 
posed by bacteria acting only at low temperatures 
and a reaction takes place between the fatty acid 
set free and the calcium salts of the cheese. The 
flavor and other qualities of the cheese do not ap- 
pear to be affected in any appreciable way. 

Milk-sugar in cheese, under the action of acid 
organisms, completely decomposes, forming lactic 
acid chiefly, wtth small amounts of some other 
products. The sugar in fresh cheese may amount to 
T or 2 per cent, but it seems to disappear from the 
cheese, for the most part, in 48 hours and completely 
within two weeks. 



334 SCIENCE AND PRACTICE OF CHEESE-MAKING 

Neutral salts and acid salts. — As already stated, 
there rarely appears to be any free acid in normal 
cheese. The calcium compounds (mainly phos- 
phates and citrates) are sufficient in amount to 
make use of the lactic acid which is formed, as 
previously explained (p. 149). The same process 
continues in the unripe cheese which previously 
begins in the milk and curd in the cheese-vat. It 
is probable that in ripened cheese the ammonia com- 
bines with the acid salts to neutralize their acidity 
more or less completely, because, in overripe cheese, 
we usually find the reaction "alkaline instead of 
acid. 

Salt. — So far as known, salt undergoes no chemical 
change in cheese-ripening. As the water decreases, 
the brine or whey of the cheese simply becomes 
stronger, as a matter of course. 

Gases. — In ripened cheese, different gases in dif- 
ferent relative proportions have been found, but 
little work has been done in connection with ched- 
dar cheese. The amounts and kinds of gases un- 
doubtedly vary according to various conditions, 
depending primarily ( i ) upon the kinds of micro- 
organisms introduced into the cheese through the 
milk, and (2) upon the temperature at which 
the cheese is ripened. The gases usually found in 
largest amounts are carbon dioxid and hydrogen. 
We have found also hydrogen sulphid. The dry 
matter in cheese is slightly reduced, owing to the 
formation and escape of gases. In one experiment 
at the New York experiment station having for its 
object a determination of the rate and amount of 
carbon dioxid formed during ripening at 60° F. by 



CHEMICAL CHANGES IN RIPENING 335 

cheddar cheese, it was found that, under normal con- 
ditions, the cheese began giving off carbon dioxid 
gas at the start and continued to do so in increasing 
amounts. At the end of two months, the rate of 
formation was still near its highest and did not 
begin to drop markedly until after about 20 weeks. 
Measurable amounts of gas were still coming from 
the cheese at the end of 32 weeks, when the experi- 
ment was discontinued. The total amount of carbon 
dioxid gas given off during the entire experiment 
was equal to 0.5 per cent of the fresh cheese, while, 
at the end of two months, it amounted to only o.i 
per cent of the original weight of the cheese. 

CONDITIONS OF CHEESE-RIPENING AND 
CHEMICAL CHANGES 

We have now considered the kinds of chemical 
compounds present in unripe cheese and some of 
the chemical changes which these compounds 
undergo. It is known that many of these changes 
take place gradually, some very slowly, but there 
is a more or less definite progression of chemical 
changes. The same cheese examined at intervals 
is found to show quite marked variations in the 
character of its proteins and protein-derived com- 
pounds. Cheeses made from the same milk under 
the same conditions of manufacture and subjected 
to different conditions during the ripening process 
show a difference in chemical composition. Also, 
cheeses manufactured under different conditions 
and ripened under uniform conditions may vary 
in the character of their nitrogen compounds. It 



;^^6 SCIENCE AND PRACTICE OF CHEESE-MAKING 

is, therefore, important to know something of the 
relation of various specific conditions to the forma- 
tion of those products which are used as a measure 
of the rate and extent of cheese-ripening. 

Method of measuring rate of cheese-ripening. — 
The development of flavor and the changes in body 
characteristic of ripening cheese may be used as 
indications of the rate and extent of the ripening 
process, but such a method is too crude for accu- 
rate work. Up to the present time, the most sat- 
isfactory method has been to determine the 
amount of different products derived from the pro- 
teins of the unripe cheese. From a chemical point 
of view, in which we consider solely the chemical 
changes occurring, without reference to their cause, 
cheese-ripening consists mainly of a change of in- 
soluble proteins into water-soluble forms that con- 
sist of other and simpler protein-derived com- 
pounds, a list of which is given above (p. 330). 
Hence, in a ripening cheese, we have progressively 
increasing amounts of proteins or protein-derived 
substances, and decreasing amounts of insoluble 
proteins. Therefore, as a measure of the rate and 
extent of ripening in cheese, we ascertain the 
amounts of water-soluble proteins and protein-de- 
rived substances and, from these amounts, reach 
conclusions as to the degree of ripening that has 
taken place. In many cases, the determination of 
the amounts of water-soluble and water-insoluble 
substances alone is sufficient; while in others it is 
necessary to know something in detail of the 
amounts of each of the protein-derived constituents. 
Stating the matter in a more comprehensive way, 



CHEMICAL CHANGES IN RIPENING 



ZZ7 



the amount of water-soluble proteins and protein- 
derived substances is used as a measure of the extent 
of cheese-ripening, considered from a chemical stand- 
point. 

The special conditions to be studied in relation 
to their influence upon the character and extent 
of chemical changes in cheese-ripening are the fol- 
lowing: (i) Time, (2) temperature, (3) moisture, 
(4) size, (5) salt, and (6) rennet-enzym. From the 
large number of data accumulated, we can give only 
enough, in somewhat condensed form, to serve as 
illustrations of the general facts discussed. 

Time and cheese-ripening. — Under all normal 
conditions that influence cheese-ripening, we find 
that, as cheese advances in age, there is a progress- 
ive change resulting in an increase of water-sol- 
uble proteins and protein-derived substances. The 
effect of time as a factor in cheese-ripening is modi- 
fied by a variety of conditions, which will be con- 
sidered later. For purpose of illustration, we give 
below averages of the results obtained under the 



SHOWING 


EFFECT 


OF TIME ON 


CHEESE-RIPENING 




Nitrogen, 


expressed as percentage of nitrogen in cheese, in form of; 






Water- 












Age 

of 


Brine- 
soluble 


soluble 
proteins 


Para- 


Case- 


Pep- 


Amino 


Ammo- 


cheese 


protein 


and de- 
rivatives 


nuclein 


oses 


tones 


acids 


nia 


Months 


Per cent 


Per cent 


Per cent 


Per cent 


Per cent 


Per cent 


Per cent 


H 


20.18 


21.44 


2.06 


3.15 


3.84 


9.88 


1.56 


3 


27.26 


30.98 


4.45 


4.56 


4.65 


14.36 


2.45 


6 


27.55 


36.15 


3.57 


4.92 


4.22 


19.96 


3.52 


9 


24.14 


43.45 


4.02 


4.59 


3.56 


26.53 


4.74 


12 


19.04 


44.75 


•3.52 


4.16 


3.95 


28.38 


5.41 


18 


12.65 


47.25 


3.40 


3.88 


2.57 


30.46 


6.62 



^^S SCIENCE AND PRACTICE OF CHEESE-MAKING 

various conditions employed. Each analysis rep- 
resents the average of the results obtained with 24 
different cheeses. 

It is noticeable that all of the soluble forms of 
nitrogen compounds increase in amount; while 
some increase continuously, like amino acids and 
ammonia, others increase for some months and 
then decrease, as paranuclein, caseoses, and pep- 
tones. Taking the total water-soluble forms in the 
cheese at the end of 18 months, we see that, of the 
total amount (47.25 per cent), 45.4 per cent was 
formed in the first six weeks, 65.5 per cent in the 
first 3 months, 16.5 per cent in the first 6 months, 
and 92 per cent in the first 9 months, which is one- 
half the entire period covered by study. In gen- 
eral, it is seen that, under uniform conditions, (i) 
the formation of water-soluble proteins and protein 
derivatives increases as cheese ages; (2) the rate of 
formation of such compounds is more rapid in the 
early stages of ripening, steadily diminishing with 
^S^'} (3) about two-thirds of these compounds are 
formed in the first 3 months and over 90 per cent in 
the first 9 months. 

Temperature and cheese-ripening. — In general, 
we find in every individual cheese that temperature 
exerts a marked influence upon the changes taking 
place in the proteins. The effect of temperature 
is, of course, modified by other conditions. As il- 
lustrative of the effect of temperature, we give in 
the table following averages in which each analysis 
embodies the analytical results furnished by four 
different cheeses ripened at the same temperatures. 



CHEMICAL CHANGES IN RIPENING 



339 



We consider also the factor of time along with that 
of temperature. 

SHOWING EFFECT OF TEMPERATURE ON CHEESE- 
RIPENING 



Tem- 
pera- 


Form of 
proteins 


Nitrogen 


expressed as percentage of nitrogen in cheese 


ture of 














ctiring- 
room 


and 
derivatives 


mos. 


3 

mos. 


6 

mos. 


9 
mos. 


12 
mos. 


18 
mos. 


Deg.F. 




Per cent 


Per cent 


Per cent 


Per cent 


Per cent 


Per cent 


32 


Total water- 
















soluble . . . 


12.80 


18.64 


23.06 


32.66 


34.02 


36.75 


55 


<{ 


20.56 


31.46 


36.09 


43.91 


45.09 


49.40 


60 


<< 


23.14 


33.69 


39.97 


46.89 


48.62 


50.16 


70 


** 


29.24 


40.13 


45.50 


50.34 


51.25 


52.67 


32 


Brine- 
















soluble 


20.58 


43.14 


36.55 


43.00 


34.48 


21.37 


55 


" 


33.01 


33.66 


35.10 


25.61 


19.26 


19.45 


60 


" 


13.89 


18.81 


19.94 


16.15 


12.32 


9.45 


70 




13.24 


13.45 


18.62 


11.83 


10.10 


7.86 


32 


Paranuclein 


1.27 


4.05 


3.44 


4.47 


4.15 


4.12 


55 


" 


2.39 


5.34 


4.25 


4.27 


3.64 


3.68 


60 


c< 


2.54 


2.71 


3.90 


4.23 


3.59 


4.73 


70 


<< 


2.03 


3.71 


2.68 


3.13 


2.45 


2.60 


32 


Caseoses. . . . 


1.05 


2.97 


5.24 


4.29 


4.17 


5.06 


55 


" 


4.08 


4.50 


5.03 


4.76 


4.73 


4.27 


60 


" 


3.44 


6.14 


6.03 


5.07 


3.68 


3.00 


70 





4.07 


4.63 


3.37 


4.24 


4.12 


3.20 


32 


Peptones . . 


1.30 


2.23 


4.53 


4.36 


4.53 


4.17 


55 


" 


3.90 


4.95 


3.99 


3.10 


3.72 


2.84 


60 


(< 


3.33 


5.99 


4.70 


3.44 


4.03 


1.80 


70 




6.81 


5.45 


3.67 


3.33 


3.51 


1.50 


32 


Amino acids 


4.82 


6.36 


8.70 


17.55 


18.73 


19.44 


55 


" 


8.69 


14.33 


19.55 


27.05 


29.00 


31.66 


60 


<< 


12.16 


14.55 


21.39 


28.84 


31.14 


33.54 


70 


" 


13.86 


22.20 


30.80 


32.68 


34.65 


37.19 


32 


Ammonia . . 


0.61 


0.61 


1.21 


1.91 


2.14 


3.98 


55 


*' 


1.50 


2.42 


3.30 


4.69 


5.57 


6.95 


60 


" 


1.67 


2.54 


3.89 


5.43 


6.12 


7.35 


70 


" 


2.47 


1 4.22 


5.71 


6.91 


7.49 


8.19 



340 SCIENCE AND PRACTICE OF CHEESE-MAKING 

Summarizing- our results, we find that, other con- 
ditions being uniform, ( i ) the water-soluble proteins 
and derivatives in cheese increase, on an aver- 
age, very closely in proportion to increase of tem- 
perature; (2) from the average of our results, there 
is an increase of 0.5 per cent of these water-soluble 
compounds for an increase of one degree of tem- 
perature between the limits of 32° and 70° F. ; (3) 
the amino acids and ammonia are formed in the cheese 
more abundantly at higher temperatures and ac- 
cumulate in the cheese, while the other water-soluble 
compounds do not appear to be regularly influenced 
by temperature in the early stages of ripening, but 
after some months they decrease in quantity with 
increase of temperature. 

Moisture and cheese-ripening. — In order to study 
the effect of moisture in cheese upon the chemical 
changes taking place in the nitrogen compounds, 
two sets of cheeses were made for comparison, 4 
different cheeses in each set being made under 
parallel conditions. One lot was covered with 
melted paraffin, in order to retard the evaporation 
of water from the cheese ; the others were left in 
the usual condition. These cheeses were all kept 
in the same curing-room at a temperature of 55° 
F. In the tabulated results following, we give the 
averages obtained with the 4 different cheeses in each 
set of experiments, those that were covered with 
paraffin being indicated as 2, the others as I. 

The cheeses covered with paraffin had somewhat 
less water when made, but the others lost water 
more rapidly, so that at the end of 3 months their 
water content was about the same. After this the 



CHEMICAL CHANGES IN RIPENING 



341 



SHOWING EFFECT OF MOISTURE IN CHEESE ON CliEESE- 

RIPENING 





Form of 
])roteins 
and de- 
rivatives 


Nitroge 


1 expressed as percentage of nitrogen 


in cheese 


No. 
of 


IV 


3 


6 


9 


12 


18 


cheese 




mos. 


mos. 


mos. 


mos. 


mos. 


mos. 


1 
2 


Total water- 
soluble . . . 


Per cent 

17.32 
17.14 


Per cent 

27.09 
27.40 


Per cent 

31.76 
36.41 


Per cent 

39.09 
46.59 


Percent 

39.80 
54.52 


Per cent 

42.77 
.56.76 


1 
2 


Brine-solu- 
^ble^ 


24.89 
21.17 


41.59 
30.42 


35.43 
49.29 


28.81 
20.16 


21.70 
9,81 


13.72 
5.30 


1 
2 


Paranuclein 


2.70 
0.87 


5.32 
4.35 


4.77 

4.45 


4.20 
4.89 


3.79 
8.01 


4.10 
7.90 


1 
2 


Caseoses . . . 


2.99 
3.58 


5.80 
3.64 


4.24 
5.38 


4.41 
5.06 


4.19 
4.32 


4.26 
4.70 


1 
2 


Peptones.. . . 


2.12 
4.49 


4.09 
4.80 


3.75 
6.19 


3.57 
4.00 


3.97 

4.43 


1.95 
3.20 


1 

2 


Amino acids 


7.50 
7.22 


9.79 
12.59 


16.00 
17.12 


21.65 
26.03 


22.89 
29.44 


26.73 
29.00 


1 
2 


Ammonia . . 


1.34 
0.98 


2.15 
1.99 


3.04 
4.26 


4.17 
6.52 


4.53 
8.27 


5.72 
12.16 


1 
2 


Water 


36.40 
35.96 


35.27 
35.00 


32.41 
33.37 


27.86 
33.24 


28.02 
32.66 


27.75 
32.10 



paraffined cheese contained considerably more water, 
the difference increasing with age, until at the end 
of 12 months it was over 4.5 pounds per 100 pounds 
of cheese. 

A general review of these results indicates the 
formation of larger amounts of water-soluble nitrogen 
compounds in cheese containing more moisture, other 
conditions being uniform. 



342 SCIENCE AND PRACTICE OF CHEESE-MAKING 

Size of cheese and ripening. — On page 320 we 
considered the influence of size of cheese upon the 
rapidity of evaporation of water from the cheese. 
Our resuUs show that the percentage loss of mois- 
ture is always greater in smaller-sized cheeses. 
This is what might naturally be expected, since the 
amount of external surface exposed for evaporation 
is greater, relative to weight, in small than in large 
cheeses. Hence, difference in size of cheese practi- 



SHOWING EFFECT OF SIZE OF CHEESE ON CHEESE- 
RIPENING 





Form of 
proteins 
and de- 
rivatives 


Nitrogen expressed as percentage of nitrogen 


in cheese 


Wei'ht 

ot 
cheese 


mos. 


3 

mos. 


6 
mos. 


9 
mos. 


12 

mos. 


18 
mos. 


Lbs. 
10 

30 


Total water- 
soluble . . . 


Per cent 

17.32 
20.56 


Per cent 

27.09 
31.46 


Per cent 

31.76 
36.09 


Per cent 

39.09 
43.91 


Per cent 

39.80 
45.09 


Per cent 

42.77 
49.40 


10 
30 


Brine-solu- 
ble^ 


24.89 
33.01 


41.59 
33.66 


35.43 
35.10 


28.81 
25.61 


21.70 
19.26 


13.72 
19.45 


10 
30 


Paranuclein 


2.70 
2.39 


5.32 
5.34 


4.77 
4.25 


4.20 
4.27 


3.79 
3.64 


4.10 
3.68 


10 
30 


Caseoses . . . 


2.90 
4.08 


5.80 
4.50 


4.24 
5.03 


4.41 
4.76 


4.19 
4.73 


4.26 
4.27 


10 
30 


Peptones . . 


2.12 
3.90 


4.09 
4.95 


3.75 
3.99 


3.57 
3.10 


3.97 
3.72 


1.95 
2.84 


to 

30 


Amino acids 


7. SO 
8.69 


9.79 
14.33 


16.00 
19.55 


21.65 
27.05 


22.89 
29.00 


26.73 
31.66 


10 
30 


Ammonia . . 


1.34 
1.50 


2.15 
2.42 


3.04 
3.30 


4.17 
4.69 


4.53 
5.57 


5.72 
6.95 


10 
30 


Water 


36.40 
36.31 


35.27 
35.11 


32.41 
33.46 


27.86 
32.29 


28.02 
31.54 


27.75 
28.56 



CHEMICAL CHANGES IK" RIPENING 343 

cally means difference in rapidity of loss of mois- 
ture, the larger cheese retaining its moisture con- 
tent longer. We should expect, then, to find es- 
sentially the same differences of ripening in cheeses 
of different size that we find in cheeses having a dif- 
ferent moisture content. To make a study of this 
point, we present on page 342 some data showing, at 
different stages of ripening, the amounts of derived 
protein compounds found in cheeses weighing respec- 
tively 30 and 10 pounds, approximately. The data 
represent averages of 4 different lots of cheeses 
ripened at 55° F. 

An examination of the table shows, in brief, that 
the larger cheeses contained more moisture after the 
early stages of ripening and that there was a more 
rapid increase in the formation of total water-soluble 
derived proteins, especially of amino acids and am- 
monia, than in the smaller cheeses. 

Amount of salt and cheese-ripening. — It is a fact 
that has long been observed by cheese-makers that 
increase of salt in cheese delays the rapidity with 
which the cheese becomes marketable, but, until 
about five years ago, no detailed chemical results 
were published in relation to the subject. In order 
to study the influence of salt upon the ripening 
process in cheese properly made and kept, there 
were made, as nearly alike as possible, four different 
lots of cheese under normal conditions. In each 
lot there were 4 cheeses weighing 30 pounds each, 
and salt was added to these in proportions varying 
as follows: No salt, 1.5, 2.5, and 5 pounds of salt 
for 1,000 pounds of milk. During the ripening, one 
^ot was kept at 32° F., one at 55° F., one at 60° F. 
and one at 70° F. On page 345 we give the aver- 



344 SCIENCE AND PRACTICE OF CHEESE-MAKING 

ages of the 4 lots of cheese kept at the different tem- 
peratures. Whether we consider each lot of cheeses 
by itself or their averages, the results are strikingly 
concordant in respect to the effect of salt upon the 
formation of proteins and their derivatives in the 
ripening process. 

We are to regard the salt in cheese as being in 
solution in the whey held by the cheese, practically 
forming a dilute brine. In common practice, 
cheese-makers add from 2 to 2^ pounds of salt to 
the curd made from 1,000 pounds of milk. Cheese 
thus salted contains about i per cent of salt. Such 
cheese usually contains about 35 to 37 per cent of 
water. Consequently, under such conditions we 
should have, approximately, a 3 per cent brine. It 
is evident that, in proportion as a cheese loses mois- 
ture by evaporation, the brine remaining becomes 
more concentrated with the advancing age of the 
cheese. 

A study of the table leads to the following state- 
ments : 

(i) The amount of salt retained in cheese is not 
proportional to the amount of salt added to the curd. 
While salt was added to the different cheeses in the 
ratio of i: 1.67: 3.33, the salt retained in the cheese 
was in the ratio of 1:1.40:2.20. Of necessity, 
a considerable proportion of the salt added to the 
cheese-curd passes into the whey. Moreover, it 
has been found by examining different portions of 
the same cheese that the salt is not commonly 
distributed with perfect uniformity through the cheese 
mass. 



SHOWING EFFECT OF SALT ON CHEESE-RIPENING 



Am't 
















of salt 
used 


Form of 
proteins 


Nitrogen expressed as percentage of nitrogen 


in cheese 


for 














1000 


and de- 


14 


3 


6 


9 


12 


18 


lbs. 


rivatives.etc. 


mos. 


mos. 


mos. 


mos. 


mos. 


mos. 


of milk 
















Lbs. 


Total water 


Per cent 


Per cent 


Per cent 


Per cent 


Per cent 


Per cent 





soluble . . . . 


23.42 


34.26 


40.52 


49.10 


51.38 


53.96 


U 


" 


21.80 


32.10 


37.67 


44.13 


45.88 


50.73 


2.V 


" 


21.67 


29.92 


34.73 


42.93 


43.52 


44.65 


5' 


** 


18.84 


27.70 


31.70 


37.64 


38.19 


39.62 





Brine -solu- 
















ble 


17.33 


27.06 


23.27 


21.82 


16.75 


12.56 


H 


" 


20.86 


28.43 


26.16 


22.38 


17.98 


12.61 


n 


" 


21.81 


24.47 


28.30 


23.54 


18.04 


13.7^ 


5 




20.73 


29.02 


32.49 


28.81 


23.41 


11. 7_ 





Paranuclein 


1.85 


4.44 


3.80 


4.66 


3.83 


3.44 


u 




2.13 


4.47 


3.52 


4.01 


3.72 


3.89 


n 


" 


2.27 


4.55 


3.51 


3.80 


3.30 


3.34 


5 




1.98 


4.35 


3.42 


3.63 


3.23 


2.96 





Caseoses . . . 


3.41 


4.94 


4.94 


5.60 


4.95 


3.87 


u 


;; .. 


3.24 


5.02 


5.17 


4.53 


3.69 


4.04 


24 


... 


3.21 


4.14 


4.98 


4.16 


3.97 


3.84 


5 




2.75 


4.14 


4.58 


4.08 


4.05 


3.77 





Peptones . . 


4.86 


5.02 


4.84 


3.47 


4.13 


2.69 


U 


" 


3.50 


5.16 


4.29 


3.54 


4.87 


3.40 


2i 


" 


4.20 


4.02 


4.02 


3.97 


3.98 


2.07 


5 




2.91 


4.42 


3.74 


3.25 


2.81 


2.14 





Amino acids 


10.22 


15.86 


22.18 


28.89 


32.19 


35.09 


U 


" 


10.46 


14.77 


20.13 


27.31 


29.33 


32.36 


2* 


" 


9.78 


13.83 


19.20 


26.72 


27.61 


29.57 


5 




8.82 


12.97 


17.34 


23.21 


24.40 


24.81 





Ammonia . . 


1.67 


2.96 


4.64 


6.54 


7.77 


8.89 


li 


" 


1.67 


2.53 


3.69 


4.69 


5.36 


7.04 


2i - 


" 


1.51 


2.36 


3.13 


4.30 


4.54 


5.83 


5 


** 


1.41 


2.03 


2.64 


3.43 


3.61 


4.70 





Per cent 
water in 
















cheese .... 


39.27 


38.22 


35.60 


35.22 


34. C9 


30.96 


14 


" 


36.66 


35.60 


33.50 


32.62 


31.61 


28. 8C 


2 4 


" 


35.69 


34.43 


32.31 


31.54 


30.99 


27.68 


5 


** 


33.63 


32.62 


29.52 


29.88 


28.61 


26. 9J 





Per cent salt 
















in cheese. . 




















14 


" 


0.59 


0.70 


0.84 


0.94 


0.92 


.... 


24 


" 


0.82 


1.20 


1.15 


1.26 


1.27 


.... 


5 




1.29 


1.50 


1.62 


1.87 


1.83 


.... 



345 



346 SCIENCE AND PRACTICE OF CHEESE-MAKING 

(2) An increase of salt in cheese-curd results in 
decreasing the amount of moisture held in cheese. 
This fact is very strikingly shown by the figures in 
the table. The cheese containing no salt retained 
most moisture, and increasing additions of salt de- 
creased the amount of moisture held in the cheese. 
The same general relation held true throughout the 
whole period of investigation. 

(3) An increase of salt in cheese was accom- 
panied by a decrease in the amount of water-soluble 
protein-derived compounds and this was true 
through the whole 18 months of the investigation. 
While this influence of salt is more noticeable in the 
case of the amino acids and ammonia, it is -clearly 
evident in the case of the paranuclein, caseoses, and 
peptones. 

(4) It is readily seen from the results embodied 
in the table that the rapidity of formation of water- 
soluble protein-derived compounds is decreased in 
the presence of increased amounts of salt in cheese. 
This is due, in part, to the effect of salt in decreas- 
ing the amount of moisture held in cheese and, in 
part, to the direct retarding action of salt upon some 
of the agents that produce the changes of cheese- 
ripening. 

Amount of rennet-enzym and cheese-ripening. — 
Before any careful studies were made of the eflfect 
Off rennet-enzym upon the chemical changes of 
cheese-ripening, there was difference of opinion 
among cheese-makers as to whether the amount 
of rennet-extract used had any influence on the 
ripening of the cheese. The various studies made 
of the subject by different investigators agree in 



CHEMICAL CHANGES IN RIPENING 



347 



showing that rennet-enzym does influence the 
rapi(Hty of the ripening process. In the results 

SHOWING EFFECT OF DIFFERENT AMOUNTS OF RENNET 
UPON CHEESE-RIPENING 





Amount 

of 
rennet- 






Nitrogen 


expressed 


as percentage 




Condition 


Water 


of nitrogen in cheese in form of : 


Age 










of 


extract 


of 


in 


Water- 








cheese 


used for 


cheese 


cheese 


soluble 


Paranu- 








1000 






proteins 


clein, cas- 


Amino 


Ammo- 




pounds 






and de- 


eoses and 


acids 


nia 




of milk 






rivatives 


peptones 






Months 


Ounces 




Per ct. 


Per ct. 


Per ct. 


Perct. 


Perct, 


1 


3 


Normal.. . . 


37.54 


18.90 


10.31 


8.36 




1 


6 


Normal.. . . 


38.06 


23.40 


13.37 


9.47 




1 


3 


Paraffined . 


38.45 


18.20 


9.95 


8.29 




1 


6 


Paraffined.. 


38.56 


24.90 


15.30 


9.63 




3 


3 


Normal.. . . 


35.59 


26.70 


13.34 


12.00 


1.87 


3 


6 


Normal.. . . 


36.25 


29.70 


15.40 


12.50 


1.86 


3 


3 


Paraffined.. 


37.97 


27.90 


13.39 


12.60 


1.96 


3 


6 


Paraffined.. 


37.61 


33.20 


16.35 


14.70 


2.18 


6 


3 


Normal .... 


33.58 


29.80 


12.02 


16.20 


2.09 


6 


6 


Normal.. . . 


33.51 


35.40 


15.11 


18.20 


2.60 


6 


3 


Paraffined.. 


37.59 


31.80 


12.84 


17.30 


2.23 


6 


6 


Paraffined.. 


36.79 


36.80 


16.76 


17.30 


2.70 


9 


3 


Normal.. . . 


31.84 


37.30 


13.47 


21.20 


2.59 


9 


6 


Normal.. . . 


30.63 


35.50 


13.00 


20.00 


2.50 


9 


3 


Paraffined.. 


36.81 


38.90 


14.93 


20.30 


3.73 


9 


6 


Paraffined.. 


35.40 


45.20 


14.36 


26.60 


4.26 


12 


3 


Normal,. . . 


28.13 


38.00 


12.05 


22.10 


4.10 


12 


6 


Normal.. . . 


29.98 


42.40 


14.38 


24.00 


3.60 


12 


3 


Paraffined.. 


36.07 


40.40 


14.10 


23.60 


2 93 


12 


6 


Paraffined.. 


34.51 


48.10 


15.34 


27.50 


4.60 


15 


3 


Normal.. . . 


26.73 


39.10 


12.05 


22.90 


4.53 


IS 


6 


Nonnal.. . . 


25.97 


43.60 


13.19 


25.50 


4.31 


IS 


3 


Paraffined.. 


34.35 


41.20 


12.96 


23.80 


4.92 


15 


6 


Parafined... 


33.21 


49.90 


16.87 


28.00 


5.54 


24 


3 


Normal.. . . 


24.76 


42.70 


12.30 


25.10 


5.06 


24 


6 


Normal.. . . 


23.33 


48.50 


14.54 


28.50 


5.84 


24 


3 


Paraffined.. 


30.93 


46.40 


11.34 


28.70 


6.52 


24 


6 


Paraffined.. 


28.22 


50.20 


11.75 


30.80 


7.92 



34^ SCIENCE AND PRACTICE OF CHEESE-MAKING 

given on page 347, the study was made with the use 
of 3 to 6 ounces of Hansen's rennet-extract in 1,000 
pounds of milk. The cheeses were made to con- 
tain about the same amount of moisture. In each 
case, one cheese was covered with paraffin in order 
to delay the evaporation of moisture, while the other 
was kept in the usual condition. 

The data in the preceding table show quite gen- 
erally a greater increase of water-soluble protein- 
derived compounds in the cheese containing the 
larger amount of rennet, other conditions being the 
same. The cheeses covered with paraffin contain 
more moisture than those not so covered and, as 
we should expect, show a larger increase of soluble 
compounds than do the other cheeses ; but here, also, 
the cheese containing the larger amount of rennet 
ripens, more rapidly than the one containing less 
rennet. 

If we examine the different classes of the water- 
soluble protein and protein-derived compounds, we 
notice that the increase caused by the increased 
use of rennet is more noticeable in the case of the 
paranuclein, caseoses and peptones than in the case 
of the amino acids and ammonia, especially during 
the first 6 or 9 months. 

GENERAL SUMMARY OF RESULTS RELAT- 
ING TO CONDITIONS OF CHEESE- 
RIPENING AND CHEMI- 
CAL CHANGES 

Reviewing briefly the results that have been pre- 
sented in the preceding pages, we have found that 



CHEMICAL CHANGES IN RIPENING 349 

different conditions affect the chemical changes in 
the protein compounds of cheese as follows : 

(i) Time. — The formation of water-soluble pro- 
tein-derived compounds increases as cheese ages, 
other conditions being uniform. The rate of increase 
is, however, not uniform, since it is much more rapid 
in the early than in the succeeding stages of ripen- 
ing. 

(2) Temperature. — The amount of soluble pro- 
tein-derived compounds increases, on an average, quite 
closely in proportion to increase of temperature, when 
other conditions are uniform. 

(3) Moisture. — Other conditions being alike, 
there is formed a larger amount of water-soluble 
protein-derived compounds in cheese containing 
more moisture than in cheese containing less mois- 
ture. 

(4) Size. — Cheeses of large size usually form 
water-soluble compounds more rapidly than smaller 
cheeses under the same conditions, because large 
cheeses lose their moisture less rapidly and after 
the early period of ripening have a higher water 
content. 

(5) Salt. — Cheese containing more salt forms 
water-soluble compounds more slowly than cheese 
containing less salt. This appears to be due, in 
part, to the direct action of salt in retarding the 
activity of one or more of the ripening agents and, 
in part, to the tendency of the salt to reduce the 
moisture content of the cheese. 

(6) Rennet. — The use of increased amounts of 
rennet-extract in cheese-making, other conditions 
being uniform, results in producing increased 



350 SCIENCE AND PRACTICE OF CHEESE-MAKING 

quantities of water-soluble protein-derived compounds 
in a given period of time, especially such compounds 
as paranuclein, caseoses and peptones. 

TRANSIENT AND CUMULATIVE PROD- 
UCTS IN CHEESE-RIPENING 

In studying the influence of various conditions 
upon the chemical changes of the protein com- 
pounds in the normal cheese-ripening process, we 
have noticed that the compounds which are grouped 
under the names, paracasein, caseoses and peptones 
usually vary within comparatively narrow limits 
and do not appear to accumulate in the cheese in 
constantly increasing quantities. These compounds 
do not appear to show much definite regularity 
in the amounts formed under different con- 
ditions. On the other hand, amino acids and am- 
monia accumulate in increasing amounts from the 
early age of the cheese during the whole process 
of normal ripening. The difference in the appar- 
ent behavior of these different classes of com- 
pounds is most readily explained by regarding the 
compounds first formed in cheese-ripening as inter- 
mediate or transient products. Thus, we find para- 
nuclein, caseoses and peptones present in the earliest 
stage of cheese-ripening, and they show a tendency 
to increase somewhat for a period of time and then 
decrease. Whatever may be the precise chemical 
relation and order of formation, the point we wish 
to keep in mind is that the amounts of these com- 
pounds do not increase regularly or accumulate 
continuously in the cheese. The extent to which 
any accumulation occurs in these transient stages 



CHEMICAL CHANGES IN RIPENING 



351 



depends upon the conditions of ripening. For ex- 
ample, at low temperatures, the transient protein 
products formed appear to pass into other forms less 
rapidly than at higher temperatures, and they tend to 
accumulate to some extent. This can be shown by 
comparing the results secured with cheeses ripened at 
32° F. and at 70° F. 



Age 

of 


Percentage of ni- 


Percentage of ni- 


Percentage of ni- 


trogen in form of 


trogen in form of 


trogen in form of 


paranuclein in 


caseoses m 


peptones in 


cheese 


cheese at 


cheese at 


cheese at 




32°F. 


70°F. 


32°F. 


70°F. 


32°F. 


70°F. 


Months 


Per cent 


Per cent 


Per cent 


Per cent 


Per cent 


Per cent 


H 


1.27 


2.03 


1.05 


4.0/ 


1.30 


6.81 


3 


4.05 


3.71 


2.97 


4.63 


2.23 


5.45 


6 


3.44 


2.68 


5.24 


3.37 


4.53 


3.67 


9 


4.47 


3.13 


4.29 


4.24 


4.36 


3.33 


12 


4.15 


2.45 


4.17 


4.12 


4.53 


3.51 


18 


4.12 


2.60 


5.06 


3.20 


4.17 


1.50 



Now, cjuite different from the behavior of these 
compounds is that of amino acids, which appear be- 
yond question to be formed from the peptones, and 
of ammonia, which is formed from the decomposition 
of amino acids. Ammonia is an end-product and the 
amino acids are end-products to a considerable extent 
in cheese normally ripened. They therefore accum- 
ulate in increasing quantities under all conditions 
that favor their formation. 



INFLUENCE OF PRODUCTS OF CHEMICAL 

CHANGE IN THE CHEESE-RIPENING 

PROCESS 

Attention has been called to the fact that chemi- 
cal changes in the proteins of cheese take place 



352 SCIENCE AND PRACTICE OF CHEESE-MAKING 

much more rapidly in the early stages of ripening 
than later. It is shown that, in the first 3 months 
of the 18-month period of study, over 65 per cent 
of the nitrogen was changed into the form of 
water-soluble compounds. How can we explain 
this observed fact that the rate of chemical change, as 
measured by the formation of water-soluble ni- 
trogen compounds, decreases as the age of cheese 
increases? The most obvious explanation is asso- 
ciated with the generally observed fact that in fer- 
mentation changes the products of the process 
weaken the action of the ferment, often inhibiting 
it altogether (p. 286). In cheese, we have an ac- 
cumulation of fermentation products in the form of 
water-soluble protein and protein-derived compounds 
and, apparently, they serve to diminish the action of 
the agents that cause the changes. 

In this connection, it is interesting to notice that 
the end-products, the amino acids and ammonia, 
appear to exert a stronger influence than do the other 
soluble protein compounds in decreasing the action of 
the ripening agents. This is indicated by the fol- 
lowing data: 









Monthly average 




Percentage of 


Percentage of 


rate of increase of 


Age 


nitrogen in form of 


nitrogen in form of 


soluble nitrogen 


of 


paranuclein, caseo- 


amino acids and 


compounds for 100 


cheese 


ses and peptones 


ammonia 


pounds of nitrogen 
in cheese 


Months 






Pounds 


H 


9.05 


11.44 


15.0 


3 


13.66 


16.81 


6.3 


6 


12.71 


23.48 


2.1 


9 


12.17 


31.27 


2.4 


12 


11.63 


33.79 


0.4 


18 


.... 


37.00 


0.4 



CHEMICAL CHANGES IN RIPENING 353 

Thus, it is seen that the first-formed products of 
cheese-ripening, paranuclein, caseoses and peptones, 
remain fairly uniform, while the amino acids and am- 
monia continuously increase. 

WHY MOISTURE INFLUENCES THE 
CHEESE-RIPENING PROCESS 

We have seen that an increased moisture content 
in cheese favors more active chemical changes in 
the process of ripening. This may be due to one or 
both 6f two effects. First, moisture in itself may 
favor the activity of the ripening ferments. It is well 
known that moisture is necessary for the action of 
ferments and that increase of moisture above a certain 
amount increases their action. Second, the presence 
of increased amounts of moisture serves to dilute the 
fermentation products and, to that extent, to counter- 
act their unfavorable effect. 

In ordinary cheese-ripening, there is a constant 
loss of moisture and this serves to make more con- 
centrated the fermentation products, which are 
increasing at the same time the moisture is de- 
creasing. Accordingly, after 3 to 6 months, differ- 
ence in moisture appears to exert a more marked 
influence upon the increased formation of soluble 
nitrogen compounds than in the early stages of 
ripening. 



CHAPTER XXV 

Causes of Chemical Changes in Cheese- 
Ripening 

A large amount of work has been done during the 
past 30 years in connection with different varieties 
of cheese, in an effort to ascertain what agents cause 
the changes taking place in cheese during the ripen- 
ing process. Many of the results have been peculiarly 
confusing and progress has been slow. Much of this 
work has been done with the hard types of cheese, 
the Emmenthaler in Europe and the cheddar in Eng- 
land and America. The scope of this book does not 
permit an historical review of these investigations, 
and the most we can hope to do, within the assigned 
limits of treatment, is to give a brief summary of 
what may be regarded as the present state of knowl- 
edge in respect to the causes of cheese-ripening in 
the case of cheddar cheese. It is well to preface our 
discussion with the statement that the amount we 
actually know at present is disappointingly small, and 
how much of what we think we know now will be 
modified by further investigation no one can con- 
fidently say. In our treatment of the causes of cheese- 
ripening, we confine our attention mainly to the 
changes that take place in the protein compounds, 
which come originally, as we know, from milk-casein ; 
because, in this portion of the cheese substance, the 
most profound and extensive changes occur, changes 
354 



CAUSES OF RIPENING CHANGES 355 

which are most intimately connected with the chang- 
ing quahties that appear in the process. As pre- 
viously stated, the cheese-ripening process, considered 
from a chemical standpoint, consists mainly in the 
change of the complex protein, paracasein, as it exists 
in cheese-curd, into a number of less complex com- 
pounds. 

Many difficulties beset the experimental study of 
cheese-ripening, some of which will be briefly noticed 
later. One of the great difficulties in the past has 
been a failure to recognize that there was more than 
one agent at work in the process of cheese-ripening. 
The investigator is always at a disadvantage when 
his point of view is too narrow, since he inevitably 
overlooks essential details, and interprets his results 
within the narrow range of his vision. This truth has 
been amply illustrated in the history of the investiga- 
tion of the causes of x:heese-ripening, since many in- 
vestigations were based upon the conception that only 
one agent was the cause; and the object of the inves- 
tigator was, unconsciously, not so much to find out 
what the real cause might be as to show that the one 
particular agency he had in mind was the actual and 
sole cause. 

We shall not attempt to treat the subject in the 
order of its historical development, but rather in the 
order in which the different agencies become most 
active in the ripening process. So far as our present 
knowledge goes, the different agents taking part in 
the change of the protein, paracasein, into simpler 
proteins and protein-derived compounds are the fol- 
lowing : 

I. Some acid, usually lactic. 



356 SCIENCE AND PRACTICE OF CHEESE-MAKING 

2. Rennet-enzym. 

3. Galactase. 

4. Micro-organisms, commonly bacteria. 

Just what part is played by each agent in the forma- 
tion of water-soluble proteins and derived proteins, 
or what interdependence there may be of the work 
of one agent upon the products of the work of 
another, we are at present able to say only in part, 
and not very definitely at that. We will now present 
an outline of what we may conceive as the distribu- 
tion of work among these different agents in the light 
of the experimental results that are now available. 
We are conscious of the possibility, or rather prob- 
ability, that some of these statements will need 
revision in the near future. 

ACTION OF ACIDS IN CHEESE-RIPENING 

The necessity of the presence of some acid in milk 
and in cheese-curd during the process of making 
cheddar cheese seems to have been well established, 
since cheese made without acid fails to ripen satis- 
factorily. In the absence of acid, little or no brine- 
soluble protein or water-soluble substance is formed, 
even after long periods of time. The work of acid, 
whatever may be the way in which its specific influ- 
ence is exerted in cheese-ripening, is something like 
this: Lactic acid is formed by the action of micro- 
organisms upon milk-sugar during the process of 
cheese-making; and its formation continues not only 
during the time the curd is in the cheese-vat but 
also in the curd as k is put in the press* and later. 
Under normal conditions, the acid continues to be 
formed so long as any milk-sugar remains in the 



CAUSES OF RIPENING CHANGES 



357 



cheese. Just how long- that is, varies according to 
conditions of manufacture and especially with the 
temperature at which the cheese is kept during the 
ripening. Under ordinary conditions, all sugar in 
cheese disappears within two weeks. Roughly 
speaking, there is between i and 2 per cent of milk- 
sugar in cheese when put in the press. How rapidly 
this undergoes change can be seen from the following 
illustrations, in which three different cheeses are 
represented : 



MILK-SUGAR IN CHEESE 



No. 1 



No. 2 



No. 3 



When put in press 

3 hours after being in press 
6 hours a£ter being in press 
12 hours after being in press 
IS hours after being in press 
2 days after being in press. . 
4 days after being in press. . 

1 week after being in press. . 

2 weeks after being in press. 



Per cent 
1.70 
1.05 
0.68 
0.68 
0.58 
0.58 
0.50 
0.10 
0.07 



Per cent 
0.77 
0.68 
0.44 



0.10 
0.04 
0.03 
0.00 



Per cent 
1.52 
0.64 

0.80 

0'.36 

0.32 

0.22 

trace 



These figures illustrate well the great variation in 
detail that may occur in the disappearance of milk- 
sugar in cheese, which means, of course, the forma- 
tion of lactic acid. 

At no stage of the process of making cheddar 
cheese, and in no cheese, do we find, under normal 
conditions, uncombined lactic acid as such, or what 
we call free lactic acid. What then becomes of the 
lactic acid known to be formed? There exist in the 
milk substances which are ready to combine with 
lactic acid as fast as it is formed and to change the 
acid from the active condition of a free acid to that 



358 SCIENCE AND PRACTICE OF CHEESE-MAKING 

of a neutral salt. These substances are chiefly lime 
compounds or compounds containing calcium as a 
base. Over one-half and, probably, about three- 
fourths, of the calcium compounds in milk are in such 
form as enable them to combine with lactic acid. A 
considerable part of the calcium in milk is in com- 
bination with phosphoric acid in the form of insoluble 
compounds, probably dicalcium phosphate in large 
part, which is held in suspension in the form of very 
minute, solid particles. Some believe that the cal- 
cium phosphate is in direct combination with casein 
in milk. The action that probably takes place can be 
represented as follows : 

Lactic acid -1- insoluble calcium phosphate = cal- 
cium lactate -|- soluble calcium phosphate (mono or 
acid-calcium phosphate). Now, mono-calcium phos- 
phate is an acid salt ; it neutralizes alkalis and tastes 
sour. Therefore, when we talk about lactic acid in 
cheese-making, we really mean the products formed 
by the action of lactic acid — calcium lactate and cal- 
cium acid phosphate. 

The first effect of the formation of these soluble 
lime salts is to promote the coagulating effect of 
rennet; and the particular thing accomplished by 
ripening milk for cheese-making is the formation in 
small, but sufficient, quantities of cakium lactate and 
soluble calcium phosphate. The succeeding changes 
in curd, the formation of a superficial film on each 
small piece of curd, the shrinking with the simul- 
taneous expulsion of whey, the stringing on a hot 
iron, the change in texture of curd to the softer, 
velvety form, resembling the meat of a chicken's 
breast, the plastic condition — these changes all 



CAUSES OF RIPENING CHANGES 



359 



appear to be associated with the continued forma- 
tion of lactic acid, resulting in larger amounts of 
calcium lactate and acid phosphate. To what ex- 
tent temperature and action of rennet-enzym share 
in producing these changes cannot be definitely 
stated now. It has been pretty satisfactorily estab- 
lished that in cheddar cheese-making there is, con- 
trary to what was believed at one time, no 
combination of any kind between the lactic acid and 
the protein of the cheese-curd, but that the acid 
formed is practically all used by the lime salts of 
tlie curd in the formation of the calcium compounds 
mentioned. 

During the cheese-making process, the cheese-curd 
or paracasein undergoes some very marked changes, 
as we have just noticed above. We have a simple 
means of measuring the extent of these changes, 
depending on the behavior of the curd when treated 
with warm (123° to 132° F.), dilute brine (a 5 per 
cent solution of common salt in water) (p. 330). 
The changes taking place and thus measured can be 
illustrated as follows, using the results of a special 
experiment, taken from the records of the New York 
experiment station : 





Per cent of pro- 
tein soluble in 
brine solution 


Per cent of pro- 
tein soluble in 
water 


When curd was cut 


3.13 

4.50 

30.15 

46.46 

96.06 




When whey was removed 




When curd was put in press 

2 hours after curd was put in press 
9i hours after curd was put in press 


3.77 
4.25 
6.48 



It is seen that the increase of the brine-soluble 
protein is very rapid between the time when the whey 



360 SCIENCE AND PRACTICE OF CHEESE-MAKING 

was removed and the curd was put in press. The 
pecuHar behavior of the curd during the cheddaring 
process is probably due to the formation of the 
brine-soluble substance; and the formation of this 
substance appears to be associated, at least in consider- 
able measure, with the formation of soluble lime salts 
resulting from the action of lactic acid. From some 
work done at the New York experiment station, it 
seems that when this brine-soluble compound is not 
formed, we do not get water-soluble substances, 
and this means that we get no cheese-ripening. In 
other words, the formation of the brine-soluble sub- 
stance appears to be prerequisite to further ripening 
changes. 

Reviewing briefly the action of acid in cheese-mak- 
ing and cheese-ripening, its chief work appears to be 
combination with the insoluble lime salts of the 
milk, producing calcium lactate and calcium acid 
phosphate. These compounds, in conjunction with 
the degree of heat used and, perhaps, also in asso- 
ciation with the action of rennet-enzym, produce 
marked changes in the curd in respect to body, 
texture and solubility in brine solution. In the 
cheese-making process, the insoluble portion of 
the curd begins to change into a form that is soluble 
in warm, 5 per cent brine, this change taking place 
rapidly during the cheddaring operation and con- 
tinuing until all the protein of the curd is in this 
form; the change appears to be complete 9 or 10 
hours after the curd is put in press. Then this 
brine-soluble curd begins to change into an in- 
soluble form, this reverse change going on very 
rapidly for a few hours and then more gradually for 
many months. From this insoluble form appear to 



CAUSES OF kiPENiNG CHANGES 361 

come the water-soluble proteins and protein deriva- 
tives that are found in cheese. Much work yet re- 
mains to be done before all the details of the action 
of acid in cheese-making are fully understood. 

ACTION OF RENNET-ENZYM IN CHEESE- 
RIPENING 

For a long time, there was doubt as to whether 
rennet-extract had anything to do with cheese-ripen- 
ing. It may be now regarded as definitely settled 
that rennet-extract contains a peptic ferment which 
has a curd-dissolving power. This fact has nothing 
necessarily to do with the question as to whether the 
peptic enzym is the same as the coagulating enzym, 
or whether two dififerent enzyms, each with a dif- 
ferent function, are present. The action of rennet 
in cheese-ripening is quite similar to that of a pepsin 
digestion. There is one important condition for the 
peptic action of the rennet-enzym — the presence of 
an amount of acid or acid salts, corresponding to 
about 0.3 per cent of lactic acid. The acid produced 
in cheese-curd and cheese furnishes the needed con- 
ditions. Whether this is the chief function of acid 
in connection with the formation of water-soluble 
proteins and derived proteins in cheese-ripening, or 
whether the salts formed by lactic acid exercise some 
influence apart from rennet action, may not be re- 
garded as satisfactorily determined at the present time. 

In order to study the eflfect of rennet-enzym in dis- 
solving the insoluble protein of cheese-curd, it is 
necessary to destroy the enzyms and micro-organisms 
present in milk. This is done by heating the milk 
to a temperature of 185° to 208° F., after which the 



2y(y2 SCIENCE AND PRACTICE OF CHEESE-MAKING 

milk is cooled and, in order to prevent bacterial action, 
treated with chloroform before being made into 
cheese. The heating of the milk to the stated tem- 
perature diminishes the readiness and completeness 
with which the rennet-extract coagulates milk-casein ; 
but the power of prompt coagulation by rennet can 
be restored by addition of calcium chlorid or carbon 
dioxid gas or any ordinary acid or acid salt. In thus 
eliminating other factors o'f cheese-ripening than ren- 
net-enzym, we necessarily produce conditions that 
do not exist in normal cheese-making, such as (i) 
heated milk, (2) absence of milk-enzyms, (3) absence 
of enzym-forming or acid-producing micro-organisms, 
and (4) the addition of calcium chlorid or carbon 
dioxid or lactic acid. Several experiments were car- 
ried on at the New York experiment station under 
the foregoing conditions and, in the table following, 
we give some of the results of this work. Lactic acid, 
when used, was added to form 0.2 per cent of the milk. 

PEPTIC ACTION OF RENNET IN CHEESE WITH AND 

WITHOUT ACID 



Age of 

cheese 

when 

analyzed 


Cheese 

made • 

with or 

without 

acid 


Percentage of nitrogen in form of : 


Water-soluble 
proteins and 

derived 
compounds 


Brine- 
soluble 
proteins 


Paranuclein , 

caseoses and 

peptones 


Amino 
acids 


Fresh 

Fresh 

12 months 

12 months 


Without 
With 

Without 
With 


6.07 

4.55 

8.47 

25.10 


3.75 
26.80 

3.36 
11.59 


5.46 

3.78 

4.51 

20.87 


0.81 
0.77 
3.96 
4.98 



In studying this table, we can readily observe the 



following indications : 



CAUSES OF RIPENING CHANGES 363 

(i) When no acid, or acid salt, is present in the 
cheese-making process, practically no changes take 
place in the protein of the green cheese, even in the 
course of a year; the different classes of compounds 
remain about the same in amount at the end of a year 
as in the fresh cheese. Rennet-enzym, in the ab- 
sence of acid or acid salts, has practically no dissolv- 
ing eff'ect on the protein of green cheese and, there- 
fore, does little or no work in the formation of water- 
soluble protein in the process of cheese-ripening. 

(2) When lactic acid was added to milk at the 
rate of 0.2 per cent, the results were in marked con- 
trast with those given when no acid was used. Thus, 
we have (a) a considerable amount of brine-soluble 
protein in the fresh cheese, and (b) a large increase 
of water-soluble nitrogen compounds at the end of 
12 months. It is noticeable that the increase in these 
water-soluble compounds is largely confined to the 
paranuclein, caseoses and peptones ; the amount of 
amino acids remains small as compared with a normal 
cheese of the same age. 

That rennet-enzym acts like pepsin in dissolving the 
protein of fresh cheese-curd has been shown by 
experimental work. Heated milk (100 cubic centi- 
meters), treated with chloroform to prevent bacterial 
action, was put into sterilized bottles ; 0.22 cubic cen- 
timeter of Hansen's fresh rennet-extract was added 
to some bottles, and to others 0.06 gram of aseptic 
scale-pepsin for each 7 grams of protein in milk. In 
the case of one-half of the bottles, 0.5 cubic centimeter 
of pure lactic acid was added. The bottles were kept 
at 60° F. The germ content was shown to be insig- 
nificant. In one set of experiments milk was used 



364 SCIENCE AND PRACTICE OF CHEESE-MAKING 

and in another, cheese. The results obtained with 
rennet-extract and commercial pepsin in the case of 
milk are given below. 



COMPARISON OF DIGESTING ACTION OF RENNET-EXTRACT 
AND COMMERCIAL PEPSIN 



Kind of 


With or 

withoitt 

lactic acid 


Age of 

milk 

when 

analyzed 


Percentage of total nitrogen in form of: 


enzym 

material 

used 


Water-soluble 

proteins and 

derivatives 


Caseoses 

and 
peptones 


Amino 
acids 




without 

Without 

With 

With 

Without 

Without 

With 

With 

Without 

Without 

With 

With 

Without 

Without 

With 

With 


Months 
Fresh 
1 
1 
1 
1 

3 
3 
3 
3 

6 
6 
6 
6 

9 
9 
9 
9 


9.98 
11.96 

8.91 
27.52 
33.51 

16.44 
11.42 
39.17 
44.47 

15.95 
10.34 
44.00 
48.76 

18.00 
10.08 
50.77 
56.96 


'5.56 

2.22 

20.39 

25.93 

8.06 

2.42 

29.01 

34.22 

12.74 

6.60 

38.46 

44.74 

12.90 

6.51 

42.66 

48.05 




Rennet . . 
Pepsin . . . 
Rennet. . . 
Pepsin . . . 

Rennet. . . 
Pepsin . . . 
Rennet.. . 
Pepsin . . . 

Rennet.. . 
Pepsin . . . 
Rennet. . . 
Pepsin. . . 

Rennet. . . 
Pepsin. . . 
Rennet.. . 
Pepsin. . . 


6.47 
6.69 
7.13 
7.58 

8.37 

9.00 

10.16 

10.25 

3.21 
3.74 
5.54 
4.02 

5.13 
3.57 
8.11 
8.91 



An examination of this table shows that there is a 
very fair parallel in the digesting action of rennet- 
extract and commercial pepsin. Thus, the action in- 
creases when acid is added ; the increase of soluble 
proteins is largely confined to caseoses and peptones ; 
the amount of amino acids remains practically 
unchanged; no ammonia is formed. The results 



CAUSES OF RIPENING CHANGES 



365 



indicate that the action of pepsin was able to 
account for all the changes observed in the case of 
rennet-extract in the presence of acid. But an inter- 
esting- difference is observable in connection with the 
results when no acid was present. We notice that, 
in the absence of acid, there is a gradual increase of 
soluble compounds in the case of rennet-extract from 
9.98 to 18.00 at the end of 9 months, but no such 
increase is seen with the commercial pepsin. This 
difference suggests that the rennet-extract contained, 
in addition to the peptic ferment proper, a digesting 
enzym not contained in the commercial pepsin ; this 
enzym shows the ability to dissolve insoluble protein 
even in the absence of acid. This observation has 
been confirmed by the work of others. 

The effect of commercial pepsin in increasing in 
cheese the amount of water-soluble proteins, when 



EFFECT OF COMMERCIAL PEPSIN IN 


CHEESE-RIPENING 








Nitrogen, e 


xpressed . 


as percentage of nitrogen 








in cheese, in 


"orm of: 








Age of 
cheese 


Form of 












No. of 












experi- 


when 


Enzyms 


Water- 




Para- 






ment 


ana- 


added 


soluble 




nuclein, 








lyzed 




proteins 
and de- 
rivatives 


B rine- 
soluble 


caseoses 
and pep- 
tones 


Amino 
acids 


Ammo' 
nia 








Per cent 


Percent 


Percent 


Perct. 


Perct. 


1 


Fresh 


Rennet- 
















extract 


4.76 


65.45 


2.41 


2.36 


.0 


1 


6 months 




















28.37 


17.14 


15.87 


6.35 


2.00 


2 


Fresh 


Rennet 
andl gm. 


6.97 


36.76 


4.11 


2.86 


.0 


2 


6 months 


pepsin 


29.80 


17.04 


16.47 


7.10 


1.91 


3 


Fresh 


Rennet 
& 15 gm. 


25.00 


59.53 


22.80 


2.20 


.0 


3 


3 months 


pepsin 


46.67 


11.61 


41.00 


5.68 


0.49 



366 SCIENCE AND PRACTICE OF CHEESE-MAKING 

used in increasing amounts, is shown by the results 
given on page 365, which were obtained in an experi- 
ment in which the cheese was made in an entirely 
normal way, except that hydrochloric acid was used 
in place of lactic acid or a ''starter." 

The following tables are taken from the records of 
the Wisconsin experiment station : 

DIGESTING ACTION OF DIFFERENT AMOUNTS OF RENNET- 
EXTRACT IN CHEESE 



Amount of 


Age of 

cheese 

when 

analyzed 


Percentage of nitrogen in form of: 


rennet- 
extract 
used 


Water soluble 
proteins and 
derivatives 


Caseoses and 
peptones 


Amino 
acids 


Ounces 
3 
12 
24 

3 

12 
24 


Months 
1 
1 
1 

3 

■ 


13.80 
18.85 
24.83 

23.33 
31.93 

34.54 


10.18 
15.17 
21.06 

11.77 
20.18 
22.80 


3.62 
3.68 
3.77 

11.56 
11.75 
11.74 



DIGESTING ACTION OF RENNET-EXTRACT AND PEPSIN 

IN CHEESE 



Cheese made 
with large 


Age of 

cheese 

when 

analyzed 


Percentage of nitrogen in form of: 


amount of 
rennet and 
with rennet 
plus pepsin 


Water-soluble 

proteins and 

derivatives 


Caseoses and 
peptones 


Amino 
acids 


Normal cheese 

Normal cheese 

and pepsin . 


70 days 
70 days 


26.67 
37.47 


14.57 
25.07 


12.10 
12.40 



We may summarize as follows the results estab- 
lished by investigation regarding the relation of ren- 
net-extract to the cheese-ripening process : 



CAUSES OF RIPENING CHANGES 367 

(i) Rennet-extract contains an enzym which has 
the power of digesting or dissolving the insoluble 
protein in cheese. 

(2) Such digesting action by rennet-extract does 
not take place in cheese which has been made without 
any acid or acid salt in the milk and curd. 

(3) The digestive action of the enzym contained 
in rennet-extract exerts its digesting power only in 
the presence of acids or acid salts. In the case of 
normal cheese, the acid formed in the cheese-making 
process is lactic acid, which, however, does not act 
as free acid, since it reacts with calcium salts, form- 
ing neutral calcium lactate and calcium acid phosphate 
and, probably, citrate. The acid salts enable the ren- 
net-enzym to exert its digesting power. The same 
general result may be accomplished by adding a free 
acid or an acid salt to milk during the cheese-making 
process. 

(4) The extent to which the digesting enzym of 
rennet-extract can act depends largely upon the degree 
of acidity developed in the cheese-making process. It 
is probable that no action begins until the equivalent 
of 0.30 per cent of lactic acid has been formed. 

(5) The products formed by rennet digestion of 
cheese proteins are largely confined to the bodies 
known as caseoses and peptones, only small 
amounts of amino acids being formed and little or 
no ammonia. 

(6) Increased use of rennet-extract in cheese- 
making results in a more rapid formation of water- 
soluble protein compounds. This is not due, as some 
formerly thought, to an increased amount of water in 
cheese, which was supposed to be a necessary result 



368 SCIENCE AND PRACTICE OF CHEESE-MAKING 

of using larger amounts of rennet-extract. Increased 
amounts of whey in cheese may, if not too excessive, 
favor more rapid action of the peptic ferment in 
rennet, because increase of whey in cheese means 
increase of milk-sugar and this means more lactic 
acid. 

(7) Commercial pepsin, when used in milk and 
cheese, behaves in a manner closely resembling 
rennet-extract; since it acts only in the presence of 
some a'cid or acid salt and forms relatively small 
amounts of amino acids as compared with caseoses 
and pept'O-aes. 

(8) Rennet-extract, therefore, contains an enzyni 
which, has the power of performing the same kind and 
amount of digesting work in cheese-ripening as pepsin. 

(9) Rennet-extract appears to contain, in addi- 
tion to the peptic ferment, another ferment which 
has the power to digest milk-casein to some extent in 
the absence of acids or acid salts. 

ACTION OF GALACTASE IN CHEESE- 
RIPENING 

The main characteristics of the milk-enzym, galac- 
tase, have been discussed already (p. 297). It has 
been shown that galactase prepared from separator- 
slime in the manner described by Babcock and Rus- 
sell contains, at least, two other enzyms. But we are 
not particularly interested to know in this discussion 
whether galactase is one or two or more enzyms ; 
the point of importance here is that milk contains a 
substance which has the power under certain condi- 
tions of converting milk-casein and the paracasein 
of cheese-curd into soluble forms of proteins and 



CAUSES OF RIPENING CHANGES 369 

protein derivatives. The fact, first discovered by 
Babcock and Russell, that there is such an enzym 
has been abundantly confirmed by work done at 
the New York experiment station and elsewhere. 
The work done by the discoverers in studying the 
properties of galactase led them to regard as one 
of the distinguishing characteristics of this enzym 
its ability to convert casein and paracasein into 
sim,pler proteins and protein derivatives, finally 
forming ammonia. On the basis of this property, 
the conclusion was reached by them that galactase 
is the chief agent in the ripening of cheddar cheese. 
Work done at the New York experiment station 
failed to confirm the conclusion that galactase 
could form ammonia in the case of either milk or 
cheese. In carrying on the work in New York, 
cheese was made from milk to which chloroform had 
been added and the cheese was kept in an atmosphere 
of chloroform, in order to prevent the action of micro- 
organisms. The only ripening agents present were, 
therefore, galactase and the enzym or enzyms of 
rennet. Cheese, thus made and kept, has de- 
veloped no ammonia, or possibly slight traces only, 
even after 24 months. The data on the next page 
illustrate this fact. 

Stated in a general way, these results show that ( i ) 
in cheese made and ripened in the presence of chloro- 
form, the amount of caseoses and peptones is largely in 
excess of the amount of amino acids; (2) the reverse 
is true in normal cheese; (3) that ammonia appears 
in normal cheese much earlier and in larger amounts 
than in chloroformed cheese, appearing in 'the latter 
only after 12 months. About as much ammonia ap- 
peared in the normal cheese in i month as appeared in 



370 SCIENCE AND PRACTICE OF CHEESE-MAKING 

the chloroformed cheese in 2 years. The amount of 
amino acids formed in the chloroformed cheese in 2 
years was about equal to the amount formed in the 
normal cheese at 5^ months. 

From these results, it is seen that, in a normal 
cheese, the amino acids continuously increase, while 



DIFFERENCE IN CHARACTER OF CHEMICAL CHANGES IN 
NORMAL AND IN CHLOROFORMED CHEESE 







Percentage of nitrogen in 


form of: 




Character of 












cheese 


Age 


Water-soluble 


Caseoses 


Amino 


Ratio 








proteins and 


and pep- 


acids 


of 


Ammo- 






derivatives 


tones 




(1) to (2) 


nia 




Months 




(1) 


(2) 






Normal cheese 


1 


16.70 


2.95 


5.42 




1.80 


0.86 


Chloroform " 


1 


8.73 


3.71 


0.86 




0.23 


.00 


Normal 


li 


20.30 


2.51 


8.49 




3.40 


1.29 


Chloroform " 


H 


12.00 


7.31 


1.82 




0.25 


0.00 


Normal 


H 


29.8() 


5.37 


12.60 




2.40 


2.51 


Chloroform " 


3h 


17.50 


10.20 


3.22 




0.31 


0.00 


Normal 


5i 


34.60 


4.97 


18.50 




3.70 


3.38 


Chloroform " 


5* 


22.30 


12.40 


4.73 




0.39 


0.00 


Normal 


7 


36.10 


3.08 


20.10 




6.50 


4.42 


Chloroform " 


7 


24.00 


10.90 


8.11 




0.74 


0.00 


Normal 


9 


37.85 


2.70 


23.50 




8.70 


4.87 


Chloroform " 


9 


29.50 


12.52 


11.60 




0.93 


0.00 


Normal " 


12 


42.30 


3.03 


24.87 




8.22 


5.69 


Chloroform '" 


12 


34.70 


11.89 


15.77 




1.33 


0.35 


Normal " 


15 


45.10 


4.47 


27.43 




6.14 


6.04 


Chloroform " 


15 


37.40 


15.68 


14.41 




0.92 


0.98 


Normal " 


18 


46.07 


2.44 


30.97 




1.27 


5.4S 


Chloroform " 


18 


37.05 


10.60 


21.06 




2.00 




Chloroform " 


24 


40.26 


21.82 


18.45 




0.84 


I'.oi 



the caseoses and peptones increase for some months 
and then decrease. In a chloroformed cheese, the dif- 
ferent classes of compounds under discussion all in- 
crease continuously from the beginning for two 
years and more. In n'ormal cheese, traces of am- 
monia appear- a-t a-n early stage of ripening, while, in 
chloroformed -cheese, the firs^t traces usually appear 



CAUSES OF RIPENING CHANGES 371 

only after the lapse of about one year, a.nd the increase 
is so very slow, that even after two years, only minute 
amounts are present. From these results, it affpears 
that while galactase performs important work in the 
ripening of cheese, it cannot be the chief factor in this 
process, because its action produces amino acids only 
very slowly, and ammonia practically not at all within 
the normal lifetime of cheddar cheese. 

One of the properties of galactase is its sensitive- 
ness to acids. In milk containing 0.15 per cent of 
hydrochloric acid, the galactase is much less active 
than in milk containing less acid. In the work done 
at the New York experiment station, the addition of 
as much as 0.2 per cent of acid materially increased 
the amount of soluble protein compounds in cheese. 
Thus, cheese made with no acid had not ripened at all 
in 3 months, while cheese made with acid under con- 
ditions otherwise the same, contained 32.37 per cent 
of its nitrogen in soluble form in 3 months. This fact 
also is not consistent with the belief that galactase 
is the chief agency in the process of cheese-ripening. 

ACTION OF MICRO-ORGANISMS IN 
CHEESE-RIPENING 

We come now to a consideration of the fourth and 
last agency which has been assigned as one of the 
causes of the chemical changes in the ripening of ched- 
dar cheese, micro-organisms. Although we discuss 
this subject last, it was, in point of time, the first to 
be studied. When the subject of cheese-ripening was 
first taken up for serious study, it was thought that 
the whole process was due to the action of bacteria, 
and all efforts were confined to this single line of 



-^y^ SCIENCE AND PRACTICE OF CHEESE-MAKING 

investigation for years, to the neglect of all other 
possibilities. The general statement of this theory is 
that the changes observed in proteins during the 
cheese-ripening process are caused by the direct action 
of micro-organisms. This has appeared in many dif- 
ferent forms according to the particular kind of micro- 
organisms to which the work was attributed. Of the 
different micro-organisms assigned as the cause of 
cheese-ripening, we can mention only one, the lactic 
acid organisms. Freudenreich has been the most 
prominent champion of this explanation of the 
changes in cheese-ripening, and he devoted years 
of investigation to the lactic acid organisms. In 
favor of this particular theory, we have the fol- 
lowing facts: (i) The lactic acid species of bacteria 
are abundant from the start and increase in num- 
bers enormously for some time, suppressing the 
growth of those bacteria that are known to have 
the power of transforming milk-casein and the 
paracasein of cheese-curd into soluble products. 
(2) There is a coincidence in time between the 
early marked advance in the formation of soluble 
proteins and the period of bacterial increase. Against 
this theory we have the following facts : ( i ) The 
lactic acid bacteria that are most useful in cheese- 
making have not been satisfactorily shown to have 
the power of changing milk-casein or paracasein into 
soluble products. (2) Ammonia is found at an early 
stage of cheese-ripening, but it has not been proved 
that lactic acid organisms produce ammonia. (3) A 
large proportion of the chemical changes in cheese 
proteins appear after the lactic acid bacteria have 
greatly decreased in number. This has been explained 
by saying that the bacteria secrete an enzym which 



CAUSES OF RIPENING CHANGES 373 

digests cheese proteins, and this continues the work 
long after the bacteria themselves disappear. The 
existence of such enzyms from such a source has not 
been satisfactorily proved yet. The weight of evi- 
dence up to the present time appears to indicate that 
the chief, if not the only, work of the lactic acid bac- 
teria is completed when milk-sugar has been changed 
into lactic acid. 

We may ask here. What justification have we for 
the germ theory in general? (i) It has been shown 
that various germs found in cheese have the power 
to cause in milk-casein and paracasein changes much 
like those observed in cheese. (2) Cheese-curd, 
treated with germicides, fails to ripen. (3) Milk, 
sterilized and made into sterile cheese, does not ripen. 
Apparently, there is no ripening, at least nothing 
like complete ripening, when there are no micro- 
organisms in cheese. The relations of certain 
micro-organisms to certain kinds of cheese, espe- 
cially of the soft type, have been satisfactorily worked 
out, but the relations to hard types of cheese, 
like the cheddar, are far from being satisfactorily 
known. 

In going over the results of investigations that bear 
on the subject of cheddar cheese-ripening, we have 
seen ( i ) that lactic acid bacteria do an important and 
necessary work in changing milk-sugar into lactic 
acid, which reacts with calcium salts in the milk, form- 
ing neutral calcium lactate and acid calcium phos- 
phate. (2) We have seen that, in the presence of the 
acid medium thus furnished by the action of lactic acid 
bacteria, the peptic enzym contained in rennet is able 
to bring about quite extensive chemical changes in the 
protein of the curd or green cheese, forming such 



374 SCIENCE AND PRACTICE OF CHEESE-MAKING 

compounds as paranuclein, caseoses and peptones and 
much smaller proportions of amino acids and little or 
no ammonia. (3) Galactase is able to perform chem- 
ical work similar in character to that of rennet-pepsin, 
but how much insoluble protein it can render soluble 
in a given period of time, we do not know. (4) 
None of the three agencies previously mentioned has 
the power of forming ammonia, as found in normal 
cheese-ripening. It, therefore, appears that bacteria 
alone must be responsible for the production of am- 
monia and of a large proportion of the amino acids. 

It is obvious that the process of cheese-ripening is 
not as simple as was once believed, but, on the con- 
trary, is exceedingly complex. We cannot say yet 
just what part each agent plays nor to what extent 
each is independent of, or dependent upon, the others. 
For example, the digesting action of rennet is clearly 
dependent upon acidity. Does the action of rennet 
have anything to do with the changing of the in- 
soluble curd into a brine-soluble substance and back 
again into a substance insoluble in brine? Or are 
these changes immediately dependent upon acid-form- 
ing bacteria? Does the rennet have any digesting 
effect until the brine-insoluble form of protein ap- 
pears? What forms of cheese proteins can galactase 
or other milk enzyms attack and under what condi- 
tions of acidity, temperature, etc.? When do the 
bacteria begin their work in rendering soluble the 
insoluble cheese proteins? Or do they act only upon 
the products formed by rennet or galactase? Is the 
bacterial work confined to one specific micro-organism, 
or is the work associative? 

We thus see that there are many details still un- 
settled; but, in view of what we think we know now, 



CAUSES OF RIPENING CHANGES 375 

we are justified in believing that the chemical changes 
of cheese-ripening are the result of several different 
kinds of fermentative agents, the precise relations of 
each of which to the details of the ripening process 
have not been satisfactorily worked out yet. 

CHEESE FLAVORS 

In connection with the ripening of cheese, the ques- 
tion of cheese flavor is, of course, one of paramount 
importance. What do we know about the origin of 
cheese flavor, the particular substance or compound 
that the flavor comes from, and the method of its 
formation? Very little, in detail. When we speak 
or think of flavors in cheese, we too commonly view 
them in a vague, misty and mysterious way. As a 
matter of fact, flavors are realities, and sometimes 
very striking ones, and they come from real things. 
Every flavor represents one or more specific chemical 
compounds. Some one chemical compound, or, it 
may be, some mixture of two or more definite 
chemical compounds, is entirely responsible for 
each and every flavor found in cheese, or, for that 
matter, anywhere else, whether pleasant or other- 
wise. 

The study of the problem of cheese flavors has 
received less attention than that of the chemical 
changes in cheese proteins, though the two questions 
are probably closely related. The questions that 
present themselves in connection with the normal 
flavors of American cheddar cheese are: (i) What 
are they? (2) Where do they come from? (3) 
What produces them or what is the manner of their 
formation ? 



376 SCIENCE AND PRACTICE OF CHEESE-MAKING 

The following facts have some bearing on these 
questions : 

(i) Newly made cheese has no real cheese flavor. 

(2) Some days or weeks must pass before real 
cheese flavor begins to appear. 

(3) The breaking down of the proteins contained 
in the cheese-curd and green cheese, resulting in the 
formation of water-soluble protein derivatives, pre- 
cedes, to some extent, the appearance of flavor in 
cheese. 

(4) Cheese flavors are produced by some chemical 
change in some compound or compounds present in 
green cheese. 

(5) In experiments where bacterial action is pre- 
vented, we do not find cheese flavor. 

(6) Neither galactase nor rennet nor pepsin ap- 
pears to be able to produce compounds that have an- 
flavor at all. 

(7) Flavor develops more quickly at higher than 
at lower temperatures. 

(8) Flavor develops more rapidly in a moist than 
in a dry cheese. 

(9) Many of the abnormal flavors of cheese can 
be traced directly to specific micro-organisms. For 
example, the oflfensive odor, usually characterized as 
*'taint," is traced to a gas-producing organism closely 
related to Bacillus coll communis, a species of bacteria 
commonly found in the intestinal tract. 

(10) Bitter flavor in cheese has been identified 
as a com.pound formed from acetaldehyd (produced 
by the alcoholic fermentation of milk-sugar) and am- 
monia, the product of bacterial action. 



CAUSES OF RIPENING CHANGES 377 

(11) The flavoring substance, whatever it is, is 
present in extremely small amounts 

(12) A cheesy flavor often develops in butter that 
is not kept at sufficiently low temperature. A distinct 
cheesy flavor is common in kumiss, when it is one o^ 
two weeks old. 

What suggestions can we derive from the preceding 
statements ? 

(i) It is quite possible that the particular com- 
pounds which furnish cheese flavor are certain pro- 
tein derivatives that are formed only after the lapse 
of some time and are much simpler than the principal 
protein found in the green cheese. This suggestion is 
supported by certain facts, (a) Cheese flavors do 
not appear until these simpler compounds begin to 
be formed, (b) Such compounds are known to be 
capable of furnishing flavors, (c) Extremely minute 
quantities of such substances go a long way in pro- 
viding flavor. Owing to the extremely minute quan- 
tities of such compounds present, the problem of 
isolating and identifying them is one of great diffi- 
culty. 

(2) We find that, in cheese cured at low tempera- 
tures, we have, in general, about the same kinds of 
compounds as in cheese cured at higher temperatures, 
but the chemical changes have not gone quite so fast 
and we have smaller quantities of these compounds 
formed that produce flavor. This is in full agreement 
with the characteristic mild flavor of cold-ripened 
cheese. 

(3) In old cheese, characterized by very strong 
flavor, especially a pungent odor and biting taste, 
ammonia is always present in large quantities as com- 



;^y8 SCIENCE and practice of cheese-making 

pared with mild-flavored cheese. The pungent flavors 
are due to ammonia compounds. 

(4) As to the material source of flavoring com- 
pounds in cheese, it is quite probable that they come 
from the changing of paracasein into simpler com- 
pounds, especially such compounds as amino acids and 
ammonia. 

(5) Fat was formerly regarded as the sole source 
of flavor in cheese, and in butter also. It is true that 
when fat in cheese decomposes, it may form a variety 
of flavoring substances, such, for example, as butyric 
acid, the characteristic flavor of rancid cheese and 
butter ; but such flavors are offensive. Fat in ched- 
dar cheese does not appear to undergo any appreciable 
change in the early stages of cheese-ripening, espe- 
cially when cheese is ripened under proper conditions 
of temperature. The decomposition of fat which gives 
rise to the small white specks sometimes observed in 
cheese ripened at low temperature does not affect the 
flavor in any way. 

(6) What is the probable cause of formation of 
cheese-flavoring compounds? It is well-known that 
the action of certain bacteria is responsible for many 
of the bad flavors of cheese. Up to the present time, 
we are unable to find any satisfactory cause other than 
micro-organisms for the real, desirable cheese flavor ; 
because, in the absence of living organisms or of the 
enzyms secreted by them, we get no flavor. 



CHAPTER XXVI 

Commercial Relations of Cheese-Ripening 

In the three chapters preceding, we have considered 
cheese-ripening in relation to (i) the conditions that 
affect the loss of weight during the ripening process, 
(2) the chemical changes taking place, and (3) the 
causes of the changes that occur in the process. In- 
cidentally, we have touched upon some of the practical 
relations of the results, but have reserved for a 
separate chapter a more detailed discussion of the 
commercial aspects of cheese-ripening. We propose 
now to take up for more extended treatment some 
of the practical applications of the results of investiga- 
tion and shall consider the following subjects: (i) 
Extent of ripening losses at cheese-factories, (2) 
value of water in cheese to dairymen, (3) moisture 
in cheese in relation to commercial quality, (4) the 
proper percentage of moisture in cheese, (5) value of 
water in cheese to consumers, (6) the reduction 
of ripening losses in commercial investigations, (7) 
the relation of conditions of ripening to the quality 
of cheese, (8) the effects of freezing on quality of 
cheese, (9) financial application of results of cheese- 
ripening investigations. 

FACTORY LOSSES IN RIPENING 

From inquiries made among cheese-makers several 
years ago, we found quite a variation in respect to 
the loss of moisture experienced by them in ripening 

379 



380 SCIENCE AND PRACTICE OF CHEESE-MAKING 

cheese. One of the most complete records, covering 
an entire season, furnished by a cheese-maker and 
factory owner who has better than average conditions 
in his curing-rooms, made the average loss of weight 
during 30 days amount to about 5 oounds per 100 
pounds of cheese. Others reported an average loss 
for the first 30 days as high as 10 pounds per 100 
pounds of cheese. The average loss was somewhere 
between these two extremes, probably not far from 7 
pounds per 100 pounds of cheese. In many fac- 
tories, conditions have not improved since the 
inquiry was made. 

VALUE OF WATER IN CHEESE TO DAIRY- 
MEN 

To the cheese-maker and producer of milk, water 
in cheese is money when put there in the right zvay 
and in the proper proportions. It is essential, in the 
process of manufacture, to incorporate water in cheese 
in quantities best suited to the requirement of the 
market for which the cheese is intended, and then it 
is equally essential that the water be kept there with 
the least possible loss. From the dairymen's stand- 
point, it is desirable to sell as much water in cheese 
as will suit the consumer. In preventing excessive 
loss of moisture, there is more water to sell at cheese 
prices, and at the same time a resulting product that 
suits the consumer better. In the conditions prevail- 
ing in many factories, high temperatures which cause 
increased loss of moisture also cause loss of fat by 
exudation from the surface of the cheese. At 75° F. 
and above, this loss becomes considerable. It has been 
shown that the loss of moisture in curing-rooms can 



COMMERCIAL CHEESE-RIPENING 38I 

be reduced to 4 pounds per 100 pounds of cheese under 
conditions practicable at factories. Using this figure 
as a basis for calculation, we find that, for every 100 
pounds of cheese, an average of 3 pounds of water 
could be saved to sell at cheese prices. This would 
mean an average increase of 30 cents, received for 
every 100 pounds of cheese. This would mean an 
average saving of $300 a season for a factory with 
a total season's output of 100,000 pounds of cheese. 
One cheese-maker reports that he calculated one sea- 
son's loss from shrinkage and found it over $600. 
While such losses may not be regarded as large in 
comparison with the total receipts, they constitute a 
noticeable percentage when viewed as unnecessary 
decrease of profits, and are Well worth saving. 

MOISTURE IN CHEESE IN RELATION TO 
COMMERCIAL QUALITY 

We have just called attention to increased re- 
ceipts coming from cheese, as a result of preventing 
excessive loss of moisture. Such saving of moisture 
not only increases the amount of cheese to be sold 
but also increases the value of the cheese from the 
standpoint of commercial quality. 

The relations existing between moisture and flavor 
are known only in a very general way. But we know 
something of the general relation between moisture 
and texture. Excessive moisture produces a degree 
of softness, which is undesirable, from a commercial 
standpoint, and at ordinary temperatures favors the 
formation of holes, a serious fault in the texture of 
cheddar cheese intended for export trade. On the 
other hand, deficient moisture favors the production 



382 SCIENCE AND PRACTICE OF CHEESE-MAKING 

of a crumbly, dry, mealy body, which is an undesir- 
able condition. High temperatures cause excessive 
loss of moisture and result in the production of 
a crumbly body. This condition injures the commer- 
cial quality of cheese and results in lower prices for 
such cheese. The following table illustrates, in a 
practical way, the effect of different temperatures 
upon texture and moisture: 

EFFECT OF TEMPERATURE OF CURING ON TEXTURE AND 
MOISTURE OF CHEESE 



Temperature of 


Texture of cheese 


Moisture lost bv 100 


curing-room 


(Perfect texture is 25) 


pounds of cheese 






Lbs. 


55°F. 


24.6 


8.5 


60°F. 


24.4 


9.0 


6S°F. 


23.6 


9.2 


70°F. 


22.0 


10.2 


7S°F. 


21.4 


10.7 


80°F. 


20.6 


31.1 



WHAT PERCENTAGE OF MOISTURE 
SHOULD CHEESE HAVE? 

Much of the cheese made in New York contains, 
in the fresh state, from 36 to 37.5 per cent of water. 
The home-trade cheese, much of which is made in the 
fall, contains 38 to 40 per cent of water. For the 
average consumer, it is safe to say, the amount of 
moisture in cheese should be not less than 33 to 35 
per cent at the time of consumption. Taking every- 
thing into consideration, it is reasonable to expect 
better results in reference to quality by holding a 
moderate amount of moisture in the green cheese and 
so ripening as to lose only a small amount of water. 



COMMERCIAL CHEESE-RIPENING 383 

than by holding an excessive amount of moisture in 
the green cheese and so ripening as to lose a larger 
amount of moisture. Some cheese-makers expect that 
they must lose lo pounds of weight per lOO pounds 
of cheese in ripening, and they attempt to meet this 
loss by retaining 40 per cent or more of moisture in 
the cheese. Such a practice cannot lead to good re- 
sults from any point of view. 

A fact that should not be lost sight of in this con- 
nection is this : Cheese ripened at such low tempera- 
tures as are favorable to diminishing the loss of 
moisture can carry larger amounts of moisture from 
the start without impairing the quality 

VALUE OF WATER IN CHEESE TO 
CONSUMERS 

In the first place, cheese that has not lost too much 
of its moisture is more pleasing to the taste of the 
average consumer. In the next place, the more com- 
pletely a cheese dries out, the harder and thicker is 
the rind and the greater the loss to the consumer. 
Most people have become accustomed to such a waste, 
but much of it is unnecessary. In a carefully ripened 
cheese, the rind is comparatively moist and only a very 
thin portion need be lost, and even this can be used 
in cooking. 

REDUCTION OF RIPENING LOSSES IN 
COMMERCIAL INVESTIGATIONS 

In 1902-3 an investigation, on a commercial scale, 
was undertaken by the Dairy Division of the Bureau 
of Animal Industry, United States Department of 



384 SCIENCE AND PRACTICE OF CHEESE-MAKING 

Agriculture, in co-operation with the experiment sta- 
tions of Wisconsin and New York, in which cheese 
was ripened at 40°, 50° and 60° F., some being cov- 
ered with paraffin. In 1903-4 the Dairy Division 




FIG. 47 — A week's temperature record of a curing-room 

HELD AT 50°F 

repeated the work, but used a lower range of 
temperatures, 28°, 34° and 40° F., and, in one case, 
5° F. The object of these investigations was to 
study on a commercial scale, under commercial con- 
ditions, (i) the influence which different tempera- 
tures have upon (a) the loss of weight in cheese, and 



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(b) the commercial qualities of 
the cheese; and (2) the in- 
fluence of covering cheese with 



loss of 
(b) the 
of the 
different 



FIG. 48— TEMPERATURE 
RECORD COVERING SEV- 
ERAL MONTHS IN CASE 
OF CURING - ROOMS 
HELD AT 28° AND 

40° F. 



paraffin upon (a) the 
weight in cheese, and 
commercial qualities 
cheese, when kept at 
temperatures. 

In the different sets of ex- 
periments, the cheeses used 
were of the following sizes : 
(i) Cheddars, 65-70 pounds; 
(2) Cheddars, 40-45 pounds; 
Flats or Twins, 30-35 pounds; 
Daisies, 20 pounds ; Young 
Americas, 10 to 12^ pounds; 
Prints, 10 pounds. 

The experiments were be- 
gun in October and extended 
through periods of time lasting 
20 to 35 weeks. The cheeses 
were obtained direct from fac- 
tories in New York, Pennsyl- 
vania, Ohio, Michigan, Illi- 
nois, Wisconsin and Iowa. They 
were 10 to 15 days old 
placed in storage. In 
cases they represented 
cheddar type manufactured for 
export trade, close-textured, 
firm-bodied and long-keeping. 
In some cases the Michigan 
type was used, which is char- 
acterized as soft-bodied, of high 
water content, more or less 

385 



when 

most 

the 



^86 SCIENCE AND PRACTICE OF CHEESE-MAKING 

porous and poor in keeping quality. Another type 
represented was the sweet-curd, more or less inter- 
mediate in qualities between the cheddar and the 
Michigan home-trade types. 

The cheeses were placed in storage during the ex- 
periments where the temperature could be very closely 
kept under control. Various devices and records are 
in use for ascertaining the uniformity of the tempera- 
ture from day to day. Two different forms of records 
are given in P'^igs. 47 and 48. 

It is not practicable to present the detailed results 
of the different experiments; we must limit our con- 
sideration to a general summary of the results. We 
shall present the results relating to the losses of ripen- 
ing under the following subdivisions : ( i ) Tempera- 
ture, (2) size of cheese, (3) type of cheese, and (4) 
coating with paraffin. 

Influence of temperature on loss of weight. — The 
results of the various investigations agree in the fol- 
lowing respects: (i) The cheese continued to lose 
weight in nearly every case as long as weighings were 
made (about 250 days), this being true at all tem- 
peratures employed (28° -60° F.). (2) The loss of 
weight was least at the lowest temperature (28° F.) 
and increased with rise of temperature. This can be 
illustrated in case of the 65-70-pound cheddars, as 
follows : 



POUNDS OF WEIGHT LOST FOR 100 POUNDS OF CHEESE 

STORED AT 




50°F. 
6.00 



60°F. 
9.90 



COMMERCIAL CHEESE-RIPENING 



387 



At the end of 27 weeks, the loss of weight was more 
than 3 times as great at 40° F. as at 28° F., and about 
5 times as great at 60° F. as at 28° F. At the end of 
35 weeks, the loss at 40° F. was just twice as great as 
at 28° F. 

Influence of size of cheese in loss of weight. — 
Small-sized cheeses, other conditions being the same, 
lost a larger amount of moisture than large cheeses. 
This tendency is shown at different temperatures by 
the following tabulated statement: 

WEIGPIT LOST PER lOO POUNDS OF CHEESE IN 20 WEEKS 



Average weight 
of cheese 


At 40°F. 


At 50°F. 


At 60°F. 


Pounds 
70 
45 
35 
124 


Pounds 
2.5 
2.7 
3.9 
4.6 


Pounds 
2.4 
3.7 
5.9 
8.1 


Pounds 

4.2 

5.1 

8.5 

12.0 



The variation in loss between different sizes is much 
less at lower than at higher temperature. 

Influence of type of cheese on loss of weight. — 
Firm-bodied, close-textured cheese loses water less 
rapidly than soft-bodied, open-textured cheese (p. 324). 

Influence of paraffin coating on loss of weight. — 
Cheese covered with parafhn loses less weight than 
cheese not so coated. By covering cheese with 
paraffin, a saving in loss of weight can be effected 
amounting to 5 or 6 pounds per 100 pounds of cheese 
at 60° F. ; and at 50° F. or below the total loss of 
weight can be reduced to i or 2 pounds per 100 
pounds of cheese in the ordinary period of ripening. 
At 40° F., the loss in case of the large-sized ched- 
dar was reduced about one-half, as compared with 



;^88 SCIENCE AND PRACTICE OF CHEESE-MAKING 

cheese not coated; at 34° F., nearly three-fourths of 
the loss was prevented; at 28° F., the losses were 
very slight, only a little over ^ pound in 2y weeks. 
The use of paraffin coating makes a greater propor- 
tionate saving in small cheeses than in large ones. In 
the case of the Young America cheeses, the loss at 
40° F. was reduced to about one-fourth of what it 
was when the cheese was uncoated 

RELATIONS OF CONDITIONS OF RIPENING 
TO QUALITY OF CHEESE 

In all the experiments mentioned, carefully selected 
experts judged the cheese from a commercial stand- 
point and scored them. These examinations were 
made at regular intervals during the continuation of 
the experiments. The results will be considered with 
reference to the effect of (i) temperature, (2) coat- 
ing with paraffin. 

Influence of temperature on quality. — Below 40° 
F., and down to 28° F., the temperature does not 
appear to have any marked effect upon the commercial 
quality of cheese. Cheese ripened at 40° was superior, 
almost without exception, to cheese ripened at higher 
temperatures. The following figures show the aver- 
age scores at different temperatures : 



Temperature Score 

40°F 95.7 

50°F 94.2 

60°F 91.7 



There was more marked deterioration in quality 
between 50° and 60° F. than between 40° and 50° F. 
In general, the higher the temperature, the greater is 



COMMERCIAL CHEESE-RIPENING 



389 



the relative deterioration of cheese in quahty for each 
degree of temperature. 

The following figures demonstrate that the dif- 
ference in quality falls mostly on the flavor (50, 
perfect), and to a less extent on texture and body 
(25, perfect) : 



Qualities 


At 40°F. 


At 50°F. 


At 60°F. 


Flavor 


47.4 
23.4 


46.4 
23.0 


44.8 


Body and texture 


22.2 







At any given time, the cheese ripened at 40° F. was 
usually better in quality than that at 50° F., and that 
at 50° F. was better than that at 60° F. The longer 
the time of ripening, the greater was the difference in 
favor of the lower temperatures, as illustrated in the 
following table: 



Age of cheese 


Score at 40°F. 


Score at SO°F. 


Score at 60°P. 


Weeks 
10 
20 
28 
35 


96.3 
93.8 
94.2 
95.3 


94.7 
91.5 
91.9 


92. 
89.7 



The cheese cured at 60° F. showed such deteriora- 
tion of quality in 20 weeks that it was sold in order 
to prevent complete loss. 

Influence of paraffin coating on quality. — The 
effect of covering cheese with paraffin was, in several 
cases, to improve the quality of the cheese so covered. 
The difference was more marked at 60° F. than at 
lower temperatures. The cheese coated with paraffin 



390 SCIENCE AND PRy\CTICE OF CHEESE-MAKING 

and ripened at 40° gave its highest score at the end 
of 35 weeks. In no case did the cheese coated with 
paraffin show any depreciation in quahty as compared 
with cheese not so covered. These results are in har- 
mony with what one might reasonably predict. Any 
condition which maintains in the cheese the uniformity 
of the moisture, when not in excess, favors the normal 
ripening changes. 

The finish of cheese w^as greatly improved by a 
coating of paraffin, since the growth of molds is pre- 
vented. In every case cheeses covered with paraffin 
were entirely clean, while the others were more or 
less heavilv coated with molds. 




FIG. 49 — SECTION OF FROZEN CHED- 
DAR CHEESE AFTER STORAGE 5V^ 

MONTHS AT 5" F. 

THE EFFECTS OF FREEZING ON QUALITY 
OF CHEESE 

Cheese placed in a room kept at 5° F. was im- 
mediately frozen hard. After a time the ends and 
sides appeared to be lumpy, due to the expansion of 
the frozen water in the cheese. After being 6 months 
in a frozen condition, the cheese was slowly thawed 



COMMERCIAL CHEESE-RIPENING 



391 



and examined. When freshly cut, the appearance was 
normal, but the surface dried out more rapidly than 
in normal cheddar cheese. The body was crumbly, as 
in the case of a cheese deficient in water. Little or no 
ripening had taken place and such insipid flavor as 
there was did not resemble anything normal. The 
frozen cheese also showed a mottled appearance, not 
shown by any other cheese ripened at 28° F. or above. 
Fig. 49 shows the appearance of a cheese after being 
kept at 5° F. for several months. 

FINANCIAL APPLICATION OF RESULTS 
OF CHEESE-RIPENING INVESTIGATIONS 

Any reduction in loss of weight or any improve- 
ment in quality in cheese-ripening means an increase 
of money that can be realized in the sale of cheese. 
We have seen that the curing of cheese at tempera- 
tures as low as 40° F. has the effect of (i) preventing 
loss of moisture and (2) increasing the value of the 
cheese. Therefore, we not only have more cheese to 
sell but can sell it at a higher price. Taking cheese 
20 weeks old as a basis for comparison, we know how 
much weight is lost at different temperatures and also 
the difference in price. From these figures the fol- 
lowing tabulated statement is given : 

MONEY RETURNS AT SEVERAL TEMPERATURES 



Temperature 
of curing 


Cured cheese 

equivalent to 100 

pounds of green 

cheese 


Market price of 1 
pound of cheese 


Receipts from 
cheese 


Degrees F. 
40 
50 
60 


Pounds 
96.2 
95.2 
92.2 


Cents 
13.275 
13.050 
12.675 


Dollars 
12.77 
12.42 
11.69 



392 SCIENCE AND PRACTICE OF CHEESE-MAKING 

These figures indicate that from lOO pounds of green 
cheese put into the curing-room we were able to re- 
ahze from that cured at 40° F., 35 cents more than 
from cheese cured at 50° F., and $1.08 more than from 
that cured at 60° F. From the cheese cured at 50° 
F., we received y}^ cents more for 100 pounds than 
from that cured at 60° F. 

If we compare our resuhs obtained with cheese cov- 
ered with paraffin with those given by cheese not so 
covered, we have the following tabulated statement: 

COMPARATIVE VALUE OF PARAFFINED AND UNPARAF- 

FINED CHEESE 



Tempei^ 
ature of 
curing- 
room 


Cured cheese 

equivalent to 100 

pounds of green 

cheese 


.Value of 1 pound 
of cheese 


Receipts from 
cheese 




Paraf- Not par- 
fined affined 


Paraf- 
fined 


Not par- 
affined 


Paraf- 
fined 


Not par- 
affined 


Deg. F. 
40 
SO 
60 


Pounds 
99.7 
99.5 
98.6 


Pounds 
96.2 
95.2 
92.2 


Cents 
14.25 
14.25 
13.75 


Cents 
14.25 
14.25 
13.50 


Dollars 
14.21 
14.19 
13.56 


Dollars 
13.70 
13.56 
12.45 



At 40° F. the difference in favor of the paraffined 
cheese is 51 cents for 100 pounds of cheese originally 
placed in the curing-room; at 50° F. the difference 
is 63 cents, and at 60° F., $1.11. Covering cheese 
with paraffin results in greater saving at higher tem- 
peratures than at lower temperatures. 

Comparing paraffined cheese cured at 40° F. with 
unparaffined cheese cured at 60° F., we find a differ- 
ence of $1.76 for 100 pounds of cheese in favor of 
the paraffined cheese and the lower temperature. 



COMMERCIAL CHEESE-RIPENING 393 

These experiments demonstrate that, by curing 
cheese at lower temperatures than those that have 
been commonly in use, it is possible to obtain a perfect, 
edible quality of cheddar cheese, which means cheese 
of clean, mild, delicate flavor, somewhat lasting, but 
not so sharp as to bite the tongue; and body such 
that a piece of cheese on the tongue dissolves com- 
pletely, leaving only a sensation of smoothness and 
richness, with no trace of harshness or grittiness. 
Such cheese can be eaten without the disagreeable 
effect of long after-tasting, which imperfectly cured 
cheese produces. The consumption of cheese can be 
greatly stimulated by making the cheese right and 
then ripening it under proper conditions of tempera- 
ture and moisture. 

METHODS OF PROVIDING PROPER CON- 
DITIONS FOR CHEESE-RIPENING 

There are three ways in which the evils resulting 
from improper conditions of ripening can be over- 
come: (i) Immediate sale and removal of cheese, 

(2) providing proper conditions in cheese-factory and 

(3) central curing-stations. We will briefly consider 
each. 

Immediate sale and removal. — In factories which 
are provided with no adequate facilities for ripening 
cheese, it has in many cases come to be a custom to 
sell the cheese before it has had a chance to deteriorate. 
So far as the cheese-factory is concerned, this system 
relieves it of responsibility for the cheese after its 
manufacture; but the factory patrons lose such ad- 
vantage as would come from providing good curing- 
rooms and holding the cheese. The buyer has an 



394 SCIENCE AND PRACTICE OF CHEESE-MAKING 

opportunity for any increased profit that comes from 
ripening the cheese properly; but too often he has no 
equipment for ripening and hastens to dispose of 
the cheese as quickly as possible. In such cases the 
cheese is put before consumers when it is still so 
green as to do injustice to the reputation of the cheese- 
maker and the cheese-factory. The most extensive 
cheese buyers usually have cold-storage plants and 
hold the cheese. 

Providing proper conditions in cheese-factory. — 
In many cases, probably in the majority of factories, 
the best interests of the factory will be conserved by 
providing a curing-room as a part of the factory 
equipment, such as is described on page 103. This is 
practicable, efficient and economical from every point 
of view. 

Central curing-stations. — In Wisconsin and Canada 
the problem of cheese-curing has been solved, to some 
extent, by providing buildings, centrally located with 
reference to a number of cheese-factories, where the 
cheese are taken as soon as practicable and stored 
until sold. Such curing-stations are provided with a 
modern cold-storage equipment and are able perfectly 
to control conditions of temperature and humidity. 
The cost of ripening cheese in this way is more than 
repaid by the increase of price received for the cured 
cheese. 



Part IV 

Methods of Making Different 
Varieties of Cheese : 

Stilton. 

English Sage. 

Cottage. 

Pasteurized Neufchatel 

Cream. 

Club. 

Edam. 

Gouda. 



CHAPTER XXVII 

Methods of Making Different Varieties 
of Cheese 

While the original purpose of the authors was 
to confine the matter of the book to the subject of 
Cheddar cheese, it has seemed desirable to devote 
one chapter to a brief description of the methods 
of making some other varieties of cheese. We have 
chosen for the most part those varieties which can 
be made with simple equipment. Such varieties as 
Swiss cheese, for example, can not be properly 
treated in a limited way. 

STILTON CHEESE 

In England Stilton cheese is the most popular of 
all blue-mold varieties. In Canada, only a small 
quantity of Stilton cheese is manufactured and, in the 
United States, a still smaller quantity. 

First stages of cheese-making process. — The 
method of making modern Stilton cheese does not 
vary greatly in the early stages from that^ of 
Cheddar cheese-making. Up to the time of salting, 
the process is practically the same in both cases. The 
main characteristic in Stilton cheese is that it should 
contain a uniform growth of blue mold distributed 
through its interior mass. 

Starting mold-formation.— The salt before bemg 
applied should be mixed with a small amount of 



397 




< 
U 
Qi 
O 

Z 

[L] 

a 
o 



MAKING DIFFERENT KINDS OF CHEESE 399 

mold growth. As a result of this even distribu- 
tion of salt through the curd, the mold becomes 
uniformly distributed over the surface of each piece 
of curd. 

Pressing cheese. — The cheese is made in ordinary 
Young-America hoops and should weigh about 12 
pounds each. The pressure should be light but con- 
tinuous for at least 48 hours. 

Ripening process. — To have Stilton cheese ripen 
into the best condition it should be kept in a damp, 
moldy cellar, where the temperature does not go 
above 65° F. Here the cheese soon becomes coated 
with blue mold, which influences the ripening 
process. 

Stilton cheese should not be consumed before it is 
at least 2 months old. 

ENGLISH SAGE CHEESE 

The manufacture of this variety is not large in 
America, but the demand for it is increasing. 

Early stages of cheese-making process. — Up to 
the time of applying the salt, the method of cheese- 
making is similar to that of cheddar cheese. At 
this time, % ounce of sage-dust is added to every 5 
pounds of salt and the mixture evenly distributed over 
the curd. 

The latest method followed in making sage 
cheese in America is to add sage flavoring-extract 
to the milk before adding the rennet. A small 
portion of the milk is made up by itself in a small 
vat. To this small amount (generally from 5 to 
10 per cent of the total) some green coloring-mat- 
ter, such as sage leaves, pieces of corn leaves, or 



400 SCIENCE AND PRACTICE OF CHEESE-MAKING 

clover leaves, is added to give the curd a green 
color. At the time of adding the salt, the uncolored 
curd and the colored curd are thoroughly mixed. 
When the cheese is pressed it presents a green, 
mottled appearance. 

Pressing cheese. — This can be done in Young- 
America hoops, but the size of each should not be 
over 5 pounds in weight. The pressure should be 
continuous for at least 48 hours. 

Ripening process. — This variety of cheese can be 
ripened in an ordinary cellar or cool room where 
the temperature does not go above 60° F. 

COTTAGE-CHEESE 

Cottage-cheese is manufactured and consumed 
extensively in the United States. The original 
Dutch cottage-cheese is the product made by al- 
lowing milk to stand until it coagulates by the 
ordinary process of souring. The curd is put into 
cotton bags to drain, and, after all free whey has 
escaped, the curd is salted. It is then pressed into 
the form of balls and is ready for immediate con- 
sumption. 

The modern method of cottage-cheese-making 
differs somewhat from the above and gives a more 
uniform quality of cheese. 

Material to use. — Skim-milk should be used, 
as whole-milk loses too much of its fat in the manu- 
facturing process. 

Preparation and use of starter. — In making cot- 
tage-cheese on a large scale, time can be saved and 
quality improved by hastening the souring of the 
milk through the use of a starter prepared in the 



MAKING DIFFERENT KINDS OF CHEESE 40I 

manner already described (p. i8). The character of 
the starter is of much importance, since the flavor of 
the cheese ahiiost entirely depends upon it. Impure 
starters may cause shmy fermentation, and from such 
curd the whey will not separate easily. 

1. Method of making cottage-cheese without 
starter. — Milk is kept at a temperature of 70° to 
75° F. until well curdled, which will usually require" 
about 48 hours. The curdled mass is then broken 
by hand or cut by a curd-knife into large pieces, 
which should be as uniform as possible. The tem- 
perature is raised to 90° F., where it is kept till 
the whey appears clear. Heating should not be 
done too rapidly, as it injures the texture of the 
cheese. From 30 to 40 minutes should be required 
for this. About 15 minutes after completion of 
the heating, or when the whey has become well 
separated from the curd, the whey is removed and 
the curd placed in muslin bags or on racks, where 
it is allowed to drain. 

The curd is then salted at the rate of I pound for 
TOO pounds of curd, or according to taste, then shaped 
into pound or half-pound balls, and finally wrapped in 
oiled paper. For the finest quality of cheese, the curd, 
before being made into balls, should be mixed with 
thick, ripened cream at the rate of i ounce of cream 
for I pound of cheese. 

2. Method of making cottage-cheese with use of 
starter. — As soon as the skim-milk is placed in the 
manufacturing vat, from 2 to 3 per cent of good 
commercial starter is added and thoroughly mixed 
through the entire mass. The subsequent steps are 
similar to those given in preceding paragraph. 



402 SCIENCE AND PRACTICE OF CHEESE-MAKING 

3. Method of making cottage-cheese with use of 
starter and rennet. — The starter is added as pre- 
viously described. About 8 hours later rennet- 
extract is added at the rate of i ounce for each 
1,000 pounds of milk. The rennet should be well 
diluted with cold water to prevent too rapid coagu- 
lation. The balance of the process is similar to that 
already described. When rennet is used, the coagula- 
tion can be secured with a smaller percentage of acid 
development. About 0.4 per cent acid in the whey 
at the time of its removal makes the best flavor and 
texture. 

4. Method of making cottage-cheese from skim- 
milk and buttermilk. — This process is now becoming- 
popular with manufacturers of cottage-cheese, 
since it affords a way of utilizing milk that might 
otherwise be wasted. The buttermilk and skim- 
milk are mixed in various proportions. The tem- 
perature for heating the milk depends on the amount 
of buttermilk and the amount of acidity. The 
lower the temperature used consistent with a good 
coagulation, the smoother will be the texture of 
the cheese. In making cottage-cheese by any of these 
methods the quality can generally be improved and 
greater uniformity secured by the use of a small 
amount of rennet. 

5. Method of making cottage-cheese by direct 
addition of hydrochloric acid. — Have the milk at 
70° to 80° F. IMeasure out pure hydrochloric acid, 
of specific gravity 1.20, at the rate of 10 ounces for 
100 pounds of milk. Dilute with ten times its 
weight of cold water and add to milk gradually, 
stirring the milk constantly while the acid is being 



MAKING DIFFERENT KINDS OF CHEESE 403 

added. Continue the stirring until the curd sepa- 
rates completely, leaving a clear whey entirely 
free from milkiness. The whey is then removed from 
the curd and the operation completed as before. In 
order to get the proper flavor, it will be necessary to 
mix with the curd some sour, thick milk or cream. 
This method does not give as satisfactory results as 
the others described. 

Qualities of cottage-cheese. — Flavor and texture 
are the most important qualities in cottage-cheese. 
The flavor should be that of mildly-soured milk 
or well-ripened cream. There should be an entire 
absence of all objectionable flavor, such as bitter 
taste, stable flavor, etc. If the cheese tastes too sour 
it is usually due to keeping too much whey in the 
curd. The use of a starter is apt to 'insure the right 
kind of flavor. The texture of cottage-cheese is 
largely dependent on the amount of moisture in the 
cheese. When the percentage of moisture is much 
below 70, the cheese is harsh, dry and sawdust-like. 
The right texture of cottage-cheese is smooth and 
free from grittiness. Difficulty is often experienced 
in securing a uniform quality at all seasons of the 
year. The trouble is generally caused by too sud- 
den changes in the temperature of the curd or in 
the development of lactic acid. Cottage-cheese 
should be kept in a cool place. It usually sells for 
5 to 10 cents per pound. 

Yield of cottage-cheese. — From lOO pounds of 
milk one should obtain from 20 to 22 pounds of cheese. 
Variation in moisture makes much variation in 
yield. 



404 SCIENCE AND PRACTICE OF CHEESE-MAKING 

Composition of cottage-cheese. — Cottage-cheese 
of the best texture contains 70 to 75 per cent of 
moisture. CurdHng milk at too high a temperature 
and heating the curd too high or too long will make 
the cheese too dry. Cottage-cheese contains about 
3.5 to 4 per cent of milk sugar and 2 to 2.5 per cent 
of nitrogen. 

PASTEURIZED NEUFCHATEL CHEESE 

This type of soft cheese is one of the most pal- 
atable of the kind. It is mild in flavor and easily 
digested. 

Method of making. — Place 30 pounds of clean, 
sweet, whole-milk in an ordinary, plain shotgun 
can. The milk should then be heated to 165° F. 
for 20 minutes by placing the can in hot water. 
After reaching this temperature it should be imme- 
diately cooled to 'J2.° F. When cool, i.o cubic cen- 
timeter of clean, commercial starter is added, 
diluted in 100 cc. of cold water. When the starter 
has been evenly stirred through the milk, rennet 
is added at the rate of 0.4 cc. to 30 pounds of 
milk. The rennet should be diluted with cold 
water, at the rate of i cc. of rennet to 99 cc. of 
water. Enough rennet should be used to give a 
firm coagulation in 12 hours. As soon as the milk 
has become firmly coagulated, it should be poured 
from the can onto a strainer-rack where the whey 
is allowed to drain from it. At this time, the whey 
dripping from the curd should have from 0.30 to 
0.32 per cent acidity. High acidity spoils the char- 
acteristic flavor and taste. While the curd is dry- 
ing, it should have the portions on the outside of 



MAKING DIFFERENT KINDS OF CHEESE 405 

the strainer stirred into the more moist portion in 
the center. This is to prevent hard particles form- 
ing from excessive drying. Some pressure may be 
used to aid in expelHng the whey. The draining of 
whey should be so regulated that, at the time of salt- 
ing, it will not have more than 0.40 per cent of acidity. 
When all free whey has escaped, salt is applied at the 
rate of i^ pounds to 100 pounds of cheese. The 
cheese is shaped by small cylindrical molds and then 
wrapped in parchment paper and tin-foil. After being 
kept for 24 hours in a cool place, the cheese is then 
ready for eating. 

CREAM CHEESE 

The manufacture of cream cheese is very similar 
to that of pasteurized Neufchatel cheese, with the 
exception that the milk is not usually pasteurized. 
Milk is modified so that it tests about 10 per cent of 
milk-fat. At the time of adding rennet, the acidity 
should not be more than 0.15 per cent. 

The cheese is shaped by square molds and each 
weighs usually about % pound. 

Sometimes cream cheese is made by adding cream 
to the curd of pasteurized Neufchatel cheese just 
before salt is applied. This method makes a cheese 
of very fine quality. 

CLUB-CHEESE 

Club-cheese is one of the most extensively used 
varieties of cheese. Practically every hotel and 
restaurant in every country uses more or less of it. 



406 SCIENCE AND TRACTICE OF CHEESE-MAKING 

The manufacturing process is simple enough, and yet 
the desired quaHty is hard to obtain. The value of 
the cheese depends entirely upon the quality of the 
constituents used. 

Method of making. — One grinds 5 pounds of 
well-ripened cheddar cheese of finest quality in an 
ordinary meat-grinding machine. After the cheese 
has been through the machine once, one pound of 
butter of the best quality is mixed with it and the 
whole mass again run through the machine. The 
mixture is then stirred and worked with the hands 
till free from all lumps. It is then packed in jars 
of some form and must be kept in a cool place. It 
is well to smear the inside walls of the jar with 
melted butter before packing the cheese in it and 
then put a thin layer of melted butter over the top 
of the packed cheese before putting on cover. 
Finest club-cheese usually sells for about 40 cents a 
pound. 

EDAM CHEESE 

Edam cheese is a sweet-curd cheese, made from 
partially skimmed milk. It comes to the market in 
the form of round, red balls, each weighing from 3^ 
to 4 pounds when cured. They are largely manu- 
factured in Northern Holland and derive their name 
from a town which is famous as a market for this 
kind of cheese 

Kind of milk used. — Alilk from which one-fourth 
to one-third of the fat has been removed is used. 
Too great pains cannot be taken in regard to the 
condition of the milk. It should be fresh, free from 



MAKING DIFFERENT KINDS OF CHEESE 407 

every trace of taint; in brief, it should be in as per- 
fect condition as it is possible to have milk. 

Treatment of milk before adding rennet. — The 
temperature of the milk should be brought up to a 
point not below 85° F. nor much above 88° F. When 
the desired temperature has become constant, then the 
coloring-matter should be added to the milk and 
thoroughly incorporated by stirring before the rennet 
is added. 

Addition of rennet to milk. — When the tempera- 
ture reaches the desired point 85° to 88° F. and 
remains there stationary, the rennet-extract is 
added, 43^ to 5J/2 ounces being taken for 1,000 
pounds of milk, or enough to coagulate the milk 
in the desired time, at the actual temperature used. 
The milk should be completely coagulated, ready 
for cutting, in about 12 to 18 minutes from the time 
the rennet is added. The same precautions observed 
in making cheddar cheese should be followed in 
making Edam cheese with reference to care in add- 
ing- the rennet, such as careful, accurate measurement, 
dilution with pure water before addition to milk, 
etc. 

Cutting the curd. — When the curd breaks clean 
across the finger, it should be cut ; the curd is cut a 
very little softer than in the cheddar process as 
ordinarily practiced. First, a vertical knife is used 
and the curd is cut lengthwise, after which it is 
allowed to stand until the slices of curd begin to 
show the separation of whey. Then the vertical 
knife is used in cutting crosswise, after which the 
horizontal knife is at once used. Any curd adher- 
ing to the bottom and sides of the vat is carefully 
removed by the hand, after which the curd-knife is 



408 SCIENCE AND PRACTICE OF CHEESE-MAKING 

again passed through the mass of curd lengthwise and 
crosswise, continuing the cutting until the curd has 
been cut as uniformly as possible into very small 
pieces. 

Treatment of curd after cutting. — When the cut- 
ting is completed, then one commences at once to 
heat the curd up to the temperature of 93° to 96° 
F. The heating is done as quickly as possible. 
While the heating is in progress, the curd is kept 
constantly agitated to prevent settling and conse- 
quent overheating. As soon as the curd shows 
signs of hardening, which the experience of the 
worker will enable him to determine, the whey is 
drawn off until the upper surface of the curd ap- 
pears, when one should commence to fill the press- 
molds. 

Filling molds, pressing and dressing cheese. — 

The molds, which are described later in detail, are 
well soaked in warm water previous to use, in 
order to prevent too sudden chilling of curd and 
consequent checking of separation of whey. As 
soon as the whey is drawn off, as indicated above, 
one commences to fill the pressing-molds. The fill- 
ing should be done as rapidly as possible to prevent 
too great cooling of curd. When the curd has been 
put into the molds, its temperature should not be 
below 88° F. Unless care is taken to keep the 
curd covered, the portion that is last put into the 
molds may become too much cooled. In making 
Fdam cheese on a small scale, it is a good plan to 
squeeze the moisture out by the hands as much as 
possible and then break it up again before putting 
in the molds, when the curd should be pressed 



MAKING DIFFERENT KINDS OF CHEESE 4O9 

into the mold by the hands as firmly as possible. 
The molds should be filled as nearly alike as pos- 
sible. The cheese should weigh from 5 to 5^ 
pounds each when ready for the press. When the 
filling of molds is completed, they are put under 
continual pressure of 20 to 25 pounds for about 25 
or 30 minutes. While the cheese is being pressed, 
some sweet whey is heated to a temperature of 125° 
or 130° F. and this whey should not be allowed to 
go below 120° F. at any time while it is being used. 
When the cheeses are taken from their molds, each 
is put into the warm whey for two minutes, then 
removed and dressed. For dressing Edam cheese 
the ordinary cheese-bandage cloth is used. This is 
cut into strips which should be long enough to 
reach entirely around the cheese and overlap an 
inch or so, and which should be wide enough to 
cover all but a small portion of the ends of the 
cheese when put in place. Before putting on the 
bandage, all rough projections should be carefully 
pared from the cheese. In putting on the bandage, 
the cheese is held in one hand and the bandage is 
wrapped carefully around the cheese, so that the 
whole cheese is covered, except a small portion 
on the upper and lower surface of the cheese. 
These bare spots are covered by small pieces of 
bandasfe cloth of a size sufficient to cover the bare 
surface. The bandage is kept wet with the warm, 
sweet whey, thus facilitating the process of dress- 
ing. After each cheese is dressed, it should be 
replaced in the pressing-mold, care being taken 
that the bandage remains in place and leaves no 
portion of the surface of the cheese uncovered and 



410 SCIENCE AND PRACTICE OF CHEESE-MAKING 

in direct contact with the mold. The cheese is then 
put under continual pressure of 60 to 120 pounds 
and kept under this continual pressure for 6 to 12 
hours. 

Salting and curing. — There are two methods 
which may be employed in salting, dry-salting and 
ivet-salting. In dry-salting, when the cheese is finally 
taken from the press, it is removed from the press- 
mold, its bandage is removed completely and the 
cheese placed in another mold, quite similar, known 
as the salting-mold. Each cheese is placed in a 
salting-mold with a coating of fine salt completely 
surrounding it. The cheese is salted in this way 
once each day for 5 or 6 days. Each day the cheese 
should be turned when it is replaced in the mold, 
so that it will not be rounded on one end more 
than another. This is for the purpose of making 
both ends uniform in shape, giving each the proper 
rounding peculiar to the shape of the cheese. In 
the method of wet-salting, the cheese is placed 
in a tank of salt brine, made by dissolving common 
salt in water in the proportion of about one pound 
of salt to 2y2 quarts of water. Each cheese is 
turned once a day and should be left in the brine 7 
or 8 days. When the cheese is taken from the 
salting-mold or salt bath it is placed in warm water 
and is given a vigorous, thorough brushing in order 
to remove all slimy or greasy substances that may 
have accumulated on the outer surface of the 
cheese. When the surface of the cheese is well 
cleansed, it is carefully wiped dry with a linen 
towel and placed upon a shelf in the curing-room. 
In being placed on the shelves, the cheeses should 



MAKING DIFFERENT KINDS OF CHEESE 4I T 

be placed in contact so as to support one another, 
until they have flattened out at both ends so much 
that they can stand upright alone. Then they are 
placed far enough apart to allow a little air space 
between them. Another method of securing the 
flattened ends is to support each cheese on opposite 
sides by wedge-shaped pieces of wood. After they 
are placed on the shelves in the curing-room, they 
are turned once a day and rubbed with the bare 
hand during the first month, twice a week during 
the second month, and once a week after that. 
When any slimy substance appears on the surface 
of the cheese, it should be washed ofl" at once with 
warm water or sweet whey. The special conditions 
of the curing-room will be noticed in detail below. 
When the cheeses are about two months old, they 
can be prepared for market, which is done in the 
following manner: They are first made smooth on 
the surface by being turned in a lathe or in some 
other manner, after which the surface is colored. 
For coloring, some carmine is dissolved in alcohol 
or ammonia to get the proper shade, and in this 
color-bath the cheeses are placed for about one min- 
ute, when they are removed and allowed to drain, 
and as soon as they are dry the outside of each 
cheese is rubbed with boiled linseed oil, in order to 
prevent checking. They are then wrapped in tin- 
foil, which is done very much like the bandaging. 
Care must be taken to put the tin-foil on so that it 
presents a smooth, neat appearance. The cheeses 
are finally packed in boxes, each box containing 12 
cheeses, arranged in two layers of six each, with a 
separate partition for each cheese. 



412 SCIENCE AND PRACTICE OF CHEESE-MAKING 

Curing-room. — Much more attention must be 
given to the condiitions of the curing-room as re- 
gards moisture and temperature than in the case of 
cheddar cheese. The curing-room should be well 
ventilated, should be quite moist and its tempera- 
ture should be kept between 50° and 65° F. These 
conditions are best secured in some form of 
cellar. 

Utensils employed in making Edam cheese. — 

Aside from the molds, continual press and salt- 
ing-vat, the same apparatus that is used in making 




FIG. 50 — EDAM PRESS-MOLD AND COVER 



cheddar cheese can be used in making Edam cheese. 
The pressing-mold is turned preferably from white 
wood or, in any case, from wood that will not taint. 
Each mold consists of two parts ; the lower part 
constitutes the main part of the mold, the upper 
portion is simply a cover. The lower portion or 
body of the' mold has several holes in the bottom, 
from which the whey flows when the cheese is 
pressed. Care must be taken to prevent these holes 
being stopped up by curd. This portion of the 
mold is about 6 inches deep and 6 inches in diam- 
eter across the top. The salting-mold has no cover 



MAKING DIFFERENT KINDS OF CHEESE 



413 



and the bottom is provided with only one hole for 
the outflow of whey ; in other respects it is much 
like the pressing-mold. 

Fig. 50 shows the external appearance of the 
press-mold with cover in position, the inner surface 
of the cover, and the inside appearance of the press- 
mold. Fig. 51 shows the press-mold and cover in 





FIG. 51 — CROSS-SEC- 
TION OF EDAM 
PRESS-MOLD AND 
COVER 



FIG. 52 — EDAM SALT- 
ING-MOLD IN CROSS- 
SECTION 



cross-section. Fig. 53 shows the salting-mold in 
external and internal appearance and Fig. 52 shows 
cross-section of the same. 

Qualities of Edam cheese. — The flavor of a per- 
fect Edam cheese is difficult to describe. It is mild, 
clean and pleasantly saline. In imperfect Edams the 
flavor is more or less sour and ofifensive. 

In body, a perfect Edam cheese is solid, rather dry 
and mealy or crumbly. This condition is secured 
by the use of partially skimmed milk, together with 
the special conditions of manufacture employed. 



414 SCIENCE AND PRACTICE OF CHEESE-MAKING 

In texture, the perfect Edam cheese should be close 
and free from pores. 

Some general remarks. — There are a few points 
which may be best brought to our attention by con- 
trasting some of the conditions used in the manufac- 
ture of Edam cheese with those employed in the 
manufacture of our American cheddar cheese. 

(i) One is made from partially skimmed milk; 
the other, when at its best, is made from whole 
milk. 




FIG. 53 — SALTING-MOLD, INSIDE AND 
OUTSIDE APPEARANCE 



(2) While it is very important in making cheddar 
cheese to have the milk in perfect condition, it is abso- 
lutely essential in making Edam cheese. 

(3) In making cheddar cheese, the removal of 
moisture is largely effected in the vat by the use of 
a higher temperature in heating the curd. In mak- 
ing Edam cheese, the removal of moisture depends 
more upon the fineness of cutting the curd and sub- 
sequent pressing. The latter process is much less 
economical as regards loss of milk constituents. 

(4) In making cheddar cheese, more or less 
lactic acid is formed according to special condi- 
tions; in making Edam cheese, every effort is made 



MAKING DIFFERENT KINDS OF CHEESE 4I5 

to hasten the process at every stage and prevent the 
formation of lactic acid. In one case, we work to 
produce an acid curd; in the other, a curd as free as 
possible from acid. 

(5) The details of salting and curing differ 
radically in the two methods. In general, the 
manufacture of Edam cheese requires labor and care 
in giving attention to many more details than the 
manufacture of cheddar cheese, however much the 
latter should have for best success. 

(6) Edam cheese sells for two or three times as 
much per pound as the best American cheddar. 

GOUDA CHEESE 

Gouda cheese is a sweet-curd cheese made from 
whole-milk. In shape, the Gouda cheese is somewhat 
like a cheddar with the sharp edges rounded off and 
sloping toward the outer circumference at the middle 
from the end faces. They usually weigh lo or 12 
pounds each, though they vary in weight from 8 to 
16 pounds. They are largely manufactured in southern 
Holland, and derive their name from the town of the 
same name. 

Kind of milk used. — Fresh, sweet milk that has 
been produced and cared for in the best possible 
manner. 

Temperature of milk before adding rennet. — The 
temperature of the milk should be brought up to a 
point not below 88° F. nor much above 90° F. When 
the desired temperature has been reached and has 
become constant, then the coloring-matter is added 
and thoroughly incorporated by stirring before the 
rennet is added. 



41 6 SCIENCE AND PRACTICE OF CHEESE-MAKING 

Addition of rennet to milk. — The rennet should 
not be added until the milk has reached the desired 
temperature (88° to 90° F.) and this temperature has 
become constant. Then one adds 4 to 5 ounces of 
fresh rennet-extract for 1,000 pounds of milk. The 
milk should be completely coagulated, ready for 
cutting, in 15 or 20 minutes. The same precautions 
should be used in adding rennet as those previously 
mentioned in connection with the manufacture of 
Edam cheese. 

Cutting the curd. — The curd should be cut when 
it is of about the hardness generally observed for 
cutting in the cheddar process. The cutting is done 
exactly as in the cheddar process except that the 
curd is cut a httle finer in the Gouda cheese. Curd 
should be about the size of peas or wheat kernels 
when ready for press and as uniform in size as 
possible. 

Treatment of curd after cutting. — When the cut- 
ting is completed, one commences at once to heat 
the curd and to stir carefully. The heating and 
constant stirring are continued until the curd 
reaches a temperature of 104° F., which should 
require from 30 to 40 minutes. When the curd be- 
comes rubber-like in feeling and makes a squeak- 
ing sound when chewed, the whey should be run 
off. The whey should be entirely sweet when it is 
removed. 

Pressing and dressing cheese. — After the whey 
is run off, the curd is put in the molds at once 
without salting. Pains should be taken in this proc- 
ess to keep the temperature of the curd as near 
100° F. as possible. Each cheese is placed under 



MAKING DIFFERENT KINDS OF CHEESE 



t,4l7 



continual pressure amounting- to lo or 20 times its 
own weight and kept for about half an hour. The 
first bandage is put on in very much the same man- 
ner as the bandage in Edam cheese-making. The 
cheese is then put in press again for about one hour. 
The first bandage is then taken off and a second one 
like the first one put on with great care, taking pains 
to make the bandage smooth, capping the ends as 
before. The cheese is then put in press again and 
left 12 hours or more. 

Salting and curing. — When the cheese is taken 
from the press the bandage is removed and it is 
placed for 24 hours in a curing-room like that used 
in curing Edam cheese, as previously described (p. 
412). Each cheese is then rubbed all over with dry 
salt until the salt begins to dissolve, and this same 
treatment is continued twice a day for ten days. 
At the end of that time, each cheese is carefully 
and thoroughly washed in warm water and dried 
with a clean linen towel. The cheeses are then 
placed on the shelves of the curing-room, turned 
once a day and rubbed like cheddars. The tempera- 
ture and moisture are controlled as described in the 
curing process of Edam cheese. If the outer surface 
of the cheese gets slimy at any time, they are care- 
fully washed in warm water and dried with clean 
towels. Under these conditions, the cheese ripens in 
2 or 3 months. 

Utensils employed in making Gouda cheese. — 
The molds, continual press and curing-room are 
the only things needed in the making of Gouda 
cheese that differ from the utensils employed in 
making cheddar cheese. The mold used for Gouda 



4l8 SCIENCE AND PRACTICE OF CHEESE-MAKING 

cheese consists of two parts, which are shown 
separate in Fig. 54, while in Fig. 55 the two parts 
are shown united, ready for pressing. These molds 
were made of heavy pressed tin. The inside diam- 
eter at the middle is about 10 inches. The diameter 
of the ends is about 6^ inches. The height of the 
mold (as seen in Fig. 55) is about 5^ inches, and 
this represents the thickness of the cheese, but by 
pushing the upper down into tlie lower portion, the 




A B 

FIG, 54 — TWO PARTS OF 

GOUDA MOLD, SHOWN 

SEPARATE 




FIG. 55 — TWO PARTS OF 
GOUDA MOLD^ UNITED 



thickness can be decreased as desired. A simple 
way to make a Gouda mold is to take two rounded 
wash basins made of pressed tin, cut them down 
so that they will be about i^A inches deep. Then 
on one portion is soldered a rim of tin about 3 
inches wide (see Fig. 54 A, or Fig. 55, lower por- 
tion of mold). On the second wash basin is sol- 
dered another rim of tin 3 inches wide, about ^ 
inch of which projects beyond the open side of 
the wash basin, the rest projecting on the other 
side (see Fig. 54 B and Fig. 55, upper portion). 
This upper part, or B, should be made of such 
diameter that it will just fit into the inside of the 



MAKING DIFFERENT KINDS OF CHEESE 419 

Other portion, as shown in Fig. 55. The upper por- 
tion is provided with two rings soldered on and the 
lower portion with two handles to facilitate handling. 
In the ends of the molds or the portions made from 
wash basins there are 18 or 20 perforations about ys 
inch in diameter, made for the purpose of letting the 
whey run out. 



Part V 

Methods of Testing 

Cheese-Factory Organization. 
Literature of Cheese-Making. 



CHAPTER XXVIII 

Methods of Testing Used in Cheese-Making 

It is our purpose in this chapter to give, for the 
most part, only an outHne of the methods of testing* 
used in connection with cheese-making, since the full 
details would occupy too much space. The methods 
to be considered cover the following substances: 

1. Fat in (i) milk, (2) whey, (3) curd, and (4) 
cheese. 

2. Acidity in (i) milk, (2) whey, (3) curd, and 
(4) cheese. 

3. Strength of rennet-extracts. 

4. Dirt and ferments in milk. 

5. Specific gravity. 

6. Hot-iron test. 

7. Casein in milk. 

THE BABCOCK TEST FOR FAT 

This is a method for determining the amount of 
fat in milk and its products. The test is based (i) on 
the action of strong sulphuric acid upon the solids 
of milk other than fat, by which the milk-fat is 
released from the restraining influence of other com- 
pounds and so is free to collect in one separate mass, 
and (2) on the use of centrifugal force, which is em- 
ployed to complete separation of the fat. The Bab- 

*For a full description of all the details of most of these methods, see 
•'Modem Methods of Testing Milk and Milk Products," published by the 
Orange Judd Company. 



424 SCIENCE AND PRACTICE OF CHEESE-MAKIN-", 

cock test finds occasion for use in connection with 
cheese-making- in the following ways : ( i ) Testing 
milk of individual patrons when dividends are made 
on the basis of the milk-fat; (2) testing milk to 
ascertain if its fat content has been seriously affected 
by skimming; (3) testing milk to use as a basis for 
estimating the yield of cheese and regulating the 
amount of salt used (p. 38) ; (4) testing whey 
and press-drippings to ascertain if the loss of fat 
is excessive, and (5) testing cheese for percentage 
of fat. 

Apparatus and materials used. — The following list 
includes the apparatus and materials used in making 
this test: (i) Test-bottles, graduated from o to 10 
per cent, so that each smallest division represents 0.20 
per cent when 17.5 cubic centimeters (18 grams) of 
milk are used; (2) pipette for measuring milk, hold- 
ing 17.6 cubic centimeters to mark; (3) measure 
for acid, holding 17.5 cubic centimeters to mark; 
(4) centrifugal machine, having a wheel 12 to 20 
inches in diameter, easily capable of being run at a 
speed of 700 to- 1,200 revolutions a minute; and (5) 
commercial sulphuric acid having a specific gravity 
between 1.82 and 1.83, preferably just 1.825 (Test- 
ing Milk, etc., pp. 32-52). 

Sampling milk for testing. — Milk that has curdled, 
or on the surface of which cream has risen and dried, 
or milk the fat of which has partially churned, is- dif- 
ficult to sample. These difficulties should not be com- 
mon in cheese-factory work, but, when they arise, 
careful attention should be given to the details pre- 
scribed for such cases (Testing Milk, etc., pp. 22- 
24). The samples to be tested must be thoroughly 
mixed. 



,<] TESTS USED IN CHEESE-MAKING 425 

Composite samples. — In order to avoid testing 
milk daily, composite samples may be prepared and 
tested at intervals of a week or ten days. Much care 
must be used in preparing and keeping composite 
samples (Testing Milk, etc., pp. 24-31). 

Method of operating the test. — (Testing Milk 
etc., pp. 53-66). In brief outline, the different 
steps are given as follows : 

( 1 ) Mix thoroughly sample of milk, which is at 
60° to 70° F. 

(2) Quickly fill pipette to mark with milk. 

(3) Run milk into test-bottle. 

(4) Fill acid-measure to mark with acid and pour 
into test-bottle. 

(5) (a) Mix milk and acid thoroughly by rotary 
motion; (b) let stand 2 to 5 minutes; and (c) mix 
again. 

(6) Put test-bottles in tester (centrifuge) and 
whirl 4 or 5 minutes at proper speed. 

(7) (a) Add fairly hot water up to neck of bot- 
tles; (b) whirl one minute; (c) add hot water to 
8 o.r 9 per cent mark; and (d) whirl one minute. 

(8) Read results at temperature of about 130° F. 
Special precautions. — The following statements 

give an outline of the particular points to be observed 
in making the test in order to insure accuracy: 
(i) Always make tests in duplicate. 

(2) Make sure that the sample is a representative 
one. 

(3) Have the temperature of the milk and acid at 
60° to 70° F. before putting in test-bottle. 

(4) Use only acid of right strength. 



426 SCIENCE AND PRACTICE OF CHEESE-MAKING 

(5) Mix milk and acid thoroughly as soon as acid 
is added. 

(6) Mix a second time after a short interval. 

(7) Make sure that the tester runs at the right 
speed and does not jar. 

(8) Use only clean, soft water in filling bottles. 

(9) Read bottles before they cool and at about 
130° F. 

(10) To guard against mistakes, read each test 
twice. 

Testing whey for fat. — The test is conducted in 
the usual way, except that special bottles having small 
necks for more accurate reading are used and less acid 
is generally sufficient (Testing Milk, etc., pp. 81- 

83). 

Testing curd and cheese. — The sample to be 
tested is weighed. Care must be taken in sampling. 
The weighed sample is treated in the test-bottle with 
about 15 cubic centimeters of hot water, after which 
the acid is added and the test completed in the usual 
way (Testing Milk, etc., pp. 83-85). 

TEST FOR ACIDITY 

Fresh milk contains substances (casein and acid 
phosphates) which neutralize alkali and in this respect 
behave like acids. The amount of this acidity is 
approximately equivalent to o.io per cent. Amounts 
of acid above this figure are usually due to the action 
of lactic acid that has been formed by the bacterial 
decomposition of the sugar in the milk. It is the 
amount of acid thus formed which we usually desire 
to determine. 



TESTS USED IN CHEESE-MAKING 427 

The method of ascertaining the acidity of milk is 
based upon the chemical action taking place between 
acids and alkalis. Acids and alkalis neutralize each 
other and form compounds called salts, which are 
neutral (neither acid nor alkaline). A substance 
used in showing whether a solution is acid, alkaline or 
neutral is called an indicator. The one in most com- 
mon use is a compound called phenolphthalein, which 
turns pink in alkali solutions and colorless in acid or 
neutral solutions. Only a few drops need be used in 
making* one test. There are several different methods 
for testing acidity, but all are alike in principle. 

Mann's acid test. — Measure exactly 50 cubic cen- 
timeters of milk into a clean porcelain cup or a glass. 
Add a few drops of phenolphthalein solution and 
then let in from a graduated burette or acidimeter, 
previously filled to the zero point, a little ''neutral- 
izer." A pink color appears and then disappears on 
stirring. Continue stirring and adding neutralizer, 
a little at a time, until the pink color remains even 
after considerable stirring. Look at graduation 
marks on burette and see how many cubic centi- 
meters have been used. Multiply this number by 
0.018 and the result is the per cent of acidity 
equivalent to lactic acid in the liquid tested (Testing 
Milk, etc., pp. 101-103). 

Farrington's alkaline tablet test. — In this form of 
test, the alkali and indicator are mixed together in the 
form of tablets. Five tablets are dissolved so as to 
make 97 cubic centimeters of solution, which is added, 
in small portions, from a graduated cylinder to 17.5 
cubic centimeters of milk until the pink color re- 
mains. Each cubic centimeter of alkali solution 



428 SCIENCE AND TRACTICE OF CHEESE-MAKING 

used stands for o.oi per cent of acidity equivalent to 
lactic test (Testing Milk, etc., pp. 103-105). 

Testing acidity of whey. — Whey is tested in the 
same manner as milk. The sample of whey tested 
should be free from all curd particles, since curd has 
some power to neutralize alkali (Testing Milk, etc., 
pp. 109-110). 

Testing acidity of cheese. — An extract of a 
weighed amount of cheese is made and this extract 
is tested for acidity in the usual way (Testing Milk, 
etc., p. no). 

Special precautions in making acidity tests. — 
In carrying out tests for acidity, certain points of the 
operation must be kept carefully in mind. 

( 1 ) The material tested must be thoroughly mixed 
before taking a sample. 

(2) The water used in preparing the alkali solu- 
tion should be neutral, soft and clean. Distilled water 
is best. 

(3) Alkaline tablets must be kept dry. 

(4) The alkali solution, whichever form is used, 
must be kept from contact with air as much as pos- 
sible to prevent change of strength. 

(5) Prepare fresh solution of alkaline tablets for 
best results. 

(6) Make tests only in a good light. 

QUICK TEST FOR ACIDITY OF MILK 

It is often desirable to ascertain quickly whether 
milk or cream contains more or less than 0.2 or 0.3 
per cent of acid. This can be done by the following 
method : An alkali solution is prepared by dissolving 
in an 8-ounce bottle 2 alkali tablets fgr each ounee 



TESTS USED IN CHEESE-MAKING 429 

of water used, A No. lO brass cartridge shell, on 
which a wire handle is soldered, is used for meas- 
uring the sample to be tested and also the alkali. A 
cartridgeful of milk is placed in a teacup and then 
a cartridgeful of the alkali solution is added. The 
contents of the cup are mixed by a rotary motion. 
If the sample tested remains white, it contains over 
0.2 per cent of acidity; if a pink color remains, the 
acidity is less than 0.2 per cent. The intensity of the 
pink color indicates the relative amount of acid pres- 
ent, since the color will be more intense in proportion 
as there is less acid. Any other measure may be used 
in place of the brass cartridge-shell, but in every case 
care must be taken to use equal amounts of milk and 
of alkali solution. 

This test can be used at the weigh-can in case of 
milks that are suspected of containing 0.2 per cent or 
more of acid. 

THE MARSCHALL TEST 

In this test the same general procedure is followed 
as in the Monrad test, but the rate of coagulation is 
observed in a different way. The following pieces 
of apparatus are used: (a) A testing cup or basin, 
of about a pint capacity, for holding the milk to 
be tested. On the inside wall of this cup there are 
graduated spaces beginning with zero at the top and 
going by half-divisions to 7 near the bottom of the 
cup, while in the bottom of the cup is a glass tube 
with a very small bore, (b) An ounce bottle with a 
mark on it to indicate 20 cc. (c) A spatula for stir- 
ring the milk, (d) A i cc. pipette. 



430 SCIENCE AND PRACTICE OF CHEESE-MAKING 

The operation of conducting this test is as follows: 
Measure with the pipette i cc. of the rennet-extract 
used and empty it into the ounce bottle, previously 
half filled with clean, cold water. Rinse the pipette 
two or three times by drawing water into it from the 
bottle and allowing it to run back into the bottle. Mix 
well by shaking. Then place the milk to be tested 
in the test-cup, setting it in a level position and allow- 
ing the milk to run out at the bottom. Taking the bot- 
tle of diluted rennet in one hand and the spatula in 
the other, watch the level of the milk in the cup. The 
moment the upper surface of the milk drops to the 
zero mark, pour the diluted rennet into the milk and 
stir well. Then leave it alone. When the milk coagu- 
lates, it stops running through the glass tube. From 
the graduated scale, read the number of spaces un- 
covered on the inside of the cup, showing how many 
divisions of milk have run out. The more slowly the 
milk coagulates, the larger the amount that runs out ; 
the more quickly the milk coagulates, the smaller the 
amount that runs out and the fewer spaces there are 
uncovered. When about 2^ spaces are uncovered, 
the milk is ready for addition of rennet. The tempera- 
ture must be watched, being tested at the start and 
finish, especially in a cold room. 

Some objectionable features of the Marschall test 
should be noticed. A difference in the size of the bore 
of the glass tube in the bottom of the cup obviously 
makes a difference in the results. It is found that the 
size of the bore of the glass tubing varies in different 
cups. Therefore, the results given by one cup can not 
be compared with those of another, unless they are 
tested on the same milk and found to agree. Special 



TESTS USED IN CHEESE-MAKING 43I 

•pains must be taken to keep the tube open, since a lit- 
tle dirt quickly stops it. The Marschall test is con- 
venient for ordinary work, but is not capable of as 
great delicacy as is the Monrad test. Results obtained 
by different workers can be compared by the Monrad 
test, but not by the Marschall test 

THE MONRAD TEST 

This test is based upon the amount of time required 
for a definite quantity of milk at a given temperature 
to become coagulated by a fixed quantity of rennet. 

The pieces of apparatus required are the following: 
(i) A tin cylinder for measuring milk, holding, when 
full, 160 cc, (2) a 5 cc. pipette, (3) a 50 cc. glass 
flask, (4) a thermometer, and (5) a half-pint tin basin. 

In testing the ripeness of milk by means of rennet- 
extract, one first prepares a dilute solution of the 
rennet, as follows : One measures with the small pi- 
pette 5 cc. of rennet-extract into the 50 cc. flask. The 
pipette is then rinsed twice with water by sucking it 
full of cold, clean water to the mark, the rinsings also 
being run into the 50 cc. flask. The flask is then filled 
with water to the 50 cc. mark, and the contents are 
well mixed by shaking. The next step is to fill the 
tin cylinder with the well-mixed milk to be tested and 
this is emptied into the half-pint basin. The milk 
must be at the temperature at which one adds the 
rennet in cheese-making, which is generally about 
84° to 86° F. To the milk at the desired tempera- 
ture, one adds 5 cc. of the diluted rennet solution, 
mixes it through the milk quickly, using the ther- 
mometer as a stirrer. The exact tinfe when the 



432 SCIENCE AND PRACTICE OF CHEESE-MAKING 

rennet-extract is added to the milk is noted by the 
second hand of a watch, and then again when the 
milk has coagulated ; the number of seconds re- 
quired to coagulate the milk is recorded. The 
exact point of coagulation ca-n be seen more 
sharply by scattering a few particles of charcoal 
(as the blackened end of a partly burned match) 
on the surface of the milk, and then with the ther- 
mometer starting the surface into motion around the 
dish. The black particles stop the instant the milk 
coagulates. By using a stop-watch great accuracy 
and delicacy can be attained. Care should be taken 
to keep the temperature of the milk at the one desired 
point, testing frequently with the thermometer; and 
in case the temperature drops, it can be raised by 
placing the basin of milk in warm water. In ordinary 
cheddar clieese-making, milk is ready for the addition 
of rennet when it coagulates in 30 to 60 seconds under 
the foregoing conditions. 

METHOD OF TESTING RENNET-EXTRACTS 

Dififerent brands of rennet-extract vary somewhat 
in their strength ; that is, the rapidity and completeness 
with which they coagulate milk when used in the same 
amount. It is therefore important to have a means of 
testing their strength, in order that their value may 
be definitely known and that cheese-makers may be 
able to know in advance of using how much they must 
use for the best results. The Monrad and Marschall 
tests are available for this purpose. 

In order to test the comparative strength of differ- 
ent rennet-extracts, one treats different portions of 
the same milk with the different extracts to be tested. 



TESTS USED IN CHEESE-MAKING 433 

In all other respects, the details of the methods pre- 
viously given are followed. All conditions must be 
kept alike in the different tests. The strength of the 
renne't-extracts is shown by the rapidity with which 
the milk is coagulated ; the stronger the rennet, the 
less the time of coagulation. 

METHOD OF TESTING PEPSIN 

Pepsin is beginning to be used in cheese-making as 
a substitute for rennet-extract. Vivian has worked 
out the important details. The scale-pepsin, of strength 
known as 1-3000, prepared from stomachs of sheep, 
is recommended. It may be used at the rate of 5 
grams for 1,000 pounds of milk. In testing scale- 
pepsin by the rennet-test, one can dissolve the scale- 
pepsin at the rate of 5 grains in 4 ounces of water 
and use this solution exactly like a rennet-extract with 
milk. It should be tested in comparison with a sam- 
ple of rennet-extract whose use in cheese-making has 
been tested, the test being made on different portions 
of the same milk. 

TESTS FOR FERMENTS AND INSOLUBLE 
DIRT IN MILK 

Those forms of micro-organisms or ferments that 
make trouble in cheese-making are not readily per- 
ceptible to the senses when milk is delivered at the 
cheese-factory, but the results of their work develop 
later either during the cheese-making process or later 
in ripening cheese. When such ferments appear, 
it is desirable to locate them in some particular herd 
or herds with a view to removal of. the causes of 



434 SCIENCE AND PRACTICE OF CPIEESE-MAKING 

trouble. It is also desirable to get an idea of the 
amount of suspended dirt in milk, as this may often 
be an indication of the general bacterial condition of 
the milk, since bacteria generally keep company with 
dirt. We have tests for accomplishing these objects. 

TEST FOR DIRT IN MILK 

The following is a quick, simple, practicable method 
for indicating in a rough way how much suspended 
dirt milk contains : Provide several granite-iron fun- 
nels 2^ or 3 inches in diameter. Place in these some 
clean absorbent cotton, making the upper surface as 
smooth and fiat as practicable and somewhat compact. 
Have these near the weighing-can so that one can be 
attached on inside of can. When milk is dumped in 
can and thoroughly mixed, take a pint and pour on 
cotton in funnel. Any suspended dirt quickly shows. 
The method might be improved by laying a circular 
piece of white muslin on top of the cotton. The test 
performed under the eyes of a patron would be con- 
vincing. Milk should contain no visible dirt in sus- 
pension. 

THE FERMENTATION OR WISCONSIN 
CURD-TEST 

Milk frequently contains objectionable forms of 
organisms or ferments that are not made perceptible 
by ordinary methods of observation. The condition 
arises particularly in milk used for cheese-making and 
may result in serious injury to the quality of the 
cheese. The Wisconsin experiment station (Wisconsin 
experiment station I2th and 15th annual reports, 
1895 and 1898) has applied certain principles to the 



TESTS USED IN CHEESE-MAKING 435 

development of a test that enables one to identify milk 
containing- certain forms of undesirable ferments likely 
to do serious injury. This method is based, in gen- 
eral, upon the plan of making conditions favorable for 
the rapid development of the ferments present in milk. 
Apparatus. — The apparatus consists of the follow- 
ing parts : ( i ) Pint glass jars or tin cans with covers, 
(2) a well-insulated tank to hold the jars, (3) rennet- 
extract, (4) a thermometer, (5) a case-knife or sim- 
ilar instrument for cutting curd, and (6) a small 
pipette for measuring rennet-extract. 

Operation of test. — The test is conducted as fol- 
lows: The jars, including- covers, just previous to 
use, are sterilized with live steam, scalding water or 
dry heat (212° F.). Each jar or can is filled about 
two-thirds full with the milk to be tested and the ster- 
ilized cover put on at once. The jars are then placed 
in the tank which is filled with water at 100° to 102° 
F. up to the upper surface of the milk in the jars. The 
temperature of the water should be kept at 100° to 
102° F. during the whole operation. To hasten the 
warming of the milk, the jars are taken out and shaken 
occasionally. The temperature of the milk is observed 
with a sterile thermometer, and when the milk has 
reached 98° F., one adds 10 drops of rennet-extract 
to each jar and mixes thoroughly by giving the con- 
tents of the jar a rotary motion. When the milk has 
coagulated, it is allowed to stand until it is firm, usu- 
ally about 20 minutes. To enable the whey to sepa- 
rate more readily, the curd is then cut fine with a 
thin knife, which must be carefully rinsed with hot 
water after finishing each jar and before using it in 
another, in order to avoid carrying contamination from 



436 SCIENCE AND PRACTICE OF CHEESE-MAKING 

one milk to another and spoiling the test. The curd 
is allowed to settle completely. When the whey has 
been separating half an hour, the samples are exam- 
ined for flavor by smelling, after which the whey 
is carefully poured out of the jars and this is repeated 
at intervals of 30 to 40 minutes for 8 hours or more. 
Under the favorable conditions of temperature, similar 
to those employed in cheese-making, the organisms 
present develop readily and reveal their presence in 
different characteristic ways. The jars are finally 
opened, any whey present is drained off, and the fol- 
lowing tests are applied : ( i ) The curd is cut into two 
pieces. The curd will be solid and free from holes 
on the cut surfaces, if the milk is not taintedv If it 
is spongy and full of holes, it contains those undesir- 
able organisms that produce gases in the curd and in- 
jure it for cheese-making, showing in the form of 
''floating curds" and ''huffy" cheese. The holes are 
usually small, their common name being "pin-holes." 
(2) The curd is examined with reference to any 
marked disagreeable odors that may be present. Some 
undesirable organisms reveal their presence by smell 
without making spongy curd, This may, perhaps, be 
best perceived by smelling of a freshly cut surface 
of the curd. Offensive odors are, of course, an unde- 
sirable indication. Special apparatus for perform- 
ing the test is furnished by dairy-supply houses, but 
pint fruit-jars and other home-made appliances will 
answer satisfactorily. 

By this method one can learn what particular lot 
of milk among several is responsible for undesirable 
fermentations. Moreover, having traced the source of 
contamination to a single herd of cows, it is easily 



TESTS USED IN CHEESE-MAKING 437 

possible, by applying the test to single cows, to ascer- 
tain which individual or individuals may be the source 
of trouble. 

Precautions. — Two points must be carefully ob- 
served in carrying out this test: (i) The tempera- 
ture must be kept as near 98° F. as possible, in 
order that the bacteria may develop as desired. 
This can be done by keeping the temperature of the 
water surrounding the jars at 100° to 102° F. The 
temperature must be watched. (2) The thermometer 
and the knife used should be made not only clean but 
sterile each time after using in one sample before 
placing them in another. 

TEST FOR SPECIFIC GRAVITY AND 
SOLIDS OF MILK 

^'Milk Testing, etc., pp. 127-132) 

Process of using Quevenne lactometer. — The 

sample of milk to be tested for specific gravity is 
brought to a temperature between 50° and 70° F. For 
convenience the milk is placed in a cylinder, which 
is nearly filled. The lactometer is carefully lowered 
into the milk until it floats and is allowed to re- 
main half a minute or more. Then one reads and 
records ( i ) the point at which the lactometer scale 
comes in contact with the upper surface of the milk; 
and (2) the temperature. The lactometer reading is 
then corrected, if the temperature is above or below 
60° F. For example, the lactometer settles in milk, 
which is at a temperature of 65° F., to the point 
marked 29. Adding to the reading for correction o.i 
for each degree above 60° F., which in this case is 0.5, 



43^ SCIENCE AND PRACTICE OF CHEESE-MAKING 

the reading becomes 29.5. This means that the spe- 
cific gravity is 1.0295. If the temperature of the 
milk were 55° F., the correction is subtracted and 
the reading becomes 28.5, equal to specific gravity 
[.0285. 

Babcock's formulas for solids and solids-not-fat. — 
The following formulas were devised by Dr. Bab- 
cock: 

( 1 ) Formula for determining solids-not-fat. — Sol- 
ids-not-fat=^L-f o.2f, in which L is the reading of 
the Quevenne lactometer and f is the per cent of fat 
in the milk. 

(2) Formula for determining solids in milk. — 
Total solids=^L+i.2f. 

These formulas can be expressed in the form of 
rules as follows : 

Ride I. — To find the per cent of solids-not-fat in 
milk, divide the reading of the Quevenne lactometer 
by 4, and to the result add the number giving the per 
cent of fat in the milk multiplied by 0.2. 

Rule 2. — To find the per cent of solids in milk, di- 
vide the Quevenne lactometer reading by 4, and to 
the result add the number giving the per cent of fat 
multiplied by 1.2. 

THE HOT-IRON TEST 

This test is used for the purpose of ascertaining 
when to remove whey from curd and when to mill 
curd. An iron of convenient size and length for hold- 
ing, as a half-inch gas-pipe, is heated fairly hot at one 
end. The iron is carefully wiped with a cloth until 
it is clean and smooth. A handful of curd is then 
taken and placed in dry cloth and squeezed by the 



TESTS USED IN CHEESE-MAKING 439 

hand, until the surface has been well dried. The curd 
is then gently pressed against the portion of the iron 
where it is hot enough to make the curd stick to 
the iron but not hot enough to scorch it. The curd is 
then carefully drawn away from the iron and, if in 
proper condition, produces fine, silky threads, the 
length of which depends upon the amount of acidity 
of the curd. 

THE HART TEST FOR CASEIN 

This test is the first one that has been proposed for 
use at cheese-factories in determining the amount of 
casein in milk. The method is based upon the follow- 
ing principles : ( i ) The property of dilute acetic acid 
to coagulate milk-casein completely without dissolving 
it. (2) The power of chloroform to remove fat from 
the precipitated casein and form a mixture of greater 
specific gravity than the casein. (3) The compacting 
of the precipitated casein into a columnar mass by 
means of carefully regulated centrifugal force. (4) 
The adaptation of a graduated tube which permits the 
percentage of casein in milk to be read directly when 
a given volume of milk is used. 

Apparatus used. — The pieces of apparatus and 
reagents used are the following: (i) Testing-tube, 
(2) centrifuge, (3) pipette, (4) cylinder, (5) dilute 
acetic acid, and (6) chloroform. 

Testing tube. — This is a long tube widening into 
a barrel shape at the end. It holds up to the neck 
about 35 cubic centimeters. The graduated portion is 
so made that each division of the scale represents o.io 
cubic centimeter, which is equivalent to 0.20 per 
cent of casein when 5 cubic centimeters of milk 



440 SCIENCE AND PRACTICE OF CHEESE-MAKING 

(equal to about 5.15 grams) are used in the test. The 
graduations extend from o to 10 per cent, thus afford- 
ing a scale sufficient to measure more than three times 
the amount of casein occurring in very rich milk. 
The tube up to the 10 per cent mark should hold 
exactly 5 cubic centimeters. 

Centrifuge. — A special centrifuge is required made 
with pockets of the proper size to hold the testing- 
tubes, having a wheel with a diameter of 15 inches, 
and geared to give a speed of 2,000 revolutions a 
minute. The centrifuge is run by hand. Each 
pocket is lined at the bottom with a wooden cork, 
furnishing an elastic cushion on which the testing- 
tube rests. Six or twelve pockets are provided. 

The pipette for measuring milk should accurately 
measure 5 cubic centimeters. 

The cylinder for measuring chloroform holds 2 
cubic centimeters to mark. 

Acetic acid. — The dilute acetic acid solution con- 
tains 0.25 per cent of acetic acid. It is recommended 
that when one prepares the dilute acetic acid with- 
out the aid of chemical control, that only glacial 
acetic acid of the highest purity (99.5 per cent) be 
used. This is conveniently prepared as follows : A 
10 per cent solution by volume is first made by dilut- 
ing ID cubic centimeters of the glacial acetic acid to 
100 cubic centimeters with water. One dilutes 25 
cubic centimeters of this 10 per cent solution to one 
liter, whith gives a solution containing 0.25 per cent 
of acetic acid. Of this solution, one uses 20 cubic 
centimeters in making the test. 

Chloroform. — This should be of the best quality. 

Method of operating the test. — (i) In each 
testing-tube, one places first about 2 cubic centimeters 



TESTS USED IN CHEESE-MAKING 44I 

of chloroform, on top of which are added about 20 
cubic centimeters of the 0.25 per cent sohition of acetic 
acid. One then accurately measures 5 cubic centi- 
meters of milk with the pipette and runs it into the 
tube, usual care being- taken to have the sample a rep- 
resentative one. The temperature of the acetic acid 
and of the milk should preferably be at about 70° F., 
but may be between 65° and 75° F. without seriously 
impairing the results. A test at low temperature tends 
to g-ive a high reading, high temperature having the 
reverse effect. 

(2) Mixing reagents and milk. — After the milk 
has been run into the testing-tube, the thumb is placed 
over the neck of the tube, the tube inverted by rotating 
the hand, in order to bring the chloroform into the 
barrel-shaped portion of the tube, and the whole is 
then shaken with a fair degree of vigor for 15 to 20 
seconds, accurately timed by a watch. The chief pur- 
pose of agitation is to cause the chloroform to mix 
intimately with the milk and take up the fat-globules. 
The shaking also serves to bring the acid into contact 
with the casein of the milk and solidify it in the form 
of a finely divided precipitate. The shaking must be 
accurately timed. Too little agitation leaves too 
much fat mixed with the casein, while, if too pro- 
longed, a partial emulsion is produced, resulting in 
a tendency toward high results and very ragged 
line between the layer of chloroform and casein 
column. After the shaking is completed, the tubes 
can be placed immediately in the centrifuge, or, 
when several samples of milk are being tested, 
they can be allowed to stand until the same opera- 
tion has been completed with all the samples. 
When there are many samples to test, it is not 



442 SCIENCE AND PRACTICE OF CHEESE-MAKING 

best to complete each one separately before going to 
the next; but the chloroform and acetic acid are intro- 
duced into all the tubes before milk is added to any. 
When the tubes are thus prepared, the milk is then 
run in and the shaking done on the whole number. 
The reason for this is that too long a contact with 
chloroform may impair the accuracy of the results of 
the test. No harm whatever results if the testing-tubes, 
after shaking and before whirling, are allowed to 
stand 15 to 30 minutes. 

Whirling the testing-tuhes. — The testing-tubes are 
then placed in the metallic pockets of the centrifuge, 
the revolving wheel of which has a diameter of 15 
inches when the tubes stand extended, allowing for 
the one-eighth inch cushion on the bottom of the 
pockets. The machine must be closed before whirl- 
ing. The centrifuge is brought to a speed of 2,000 
revolutions and then run at this rate 73^ to 8 minutes. 
The range of variation of revolutions may extend 
from 1,950 to 2,050 without causing a serious mistake 
in the results. For the proper control of the speed 
in a hand-centrifuge, the use of a metronome is 
necessary. In a centrifuge of the diameter mentioned 
above, it is necessary to turn the crank 55 or 56 revo- 
lutions a minute to develop a speed of 2,000 revolu- 
tions. The metronome is set so as to beat that number 
of times a minute and the operator, after a little 
practice, can regulate the turning so as to make one 
revolution of the crank with each beat of the metro- 
nome. When the whirling is completed, the testing- 
tubes are removed from the centrifuge and placed 
in a rack that will support them in an upright posi- 
tion. If the test has been successful, the chloroform, 
holding the fat, is found at the bottom of the test- 



TESTS USED IN CHEESE-MAKING 443 

iiig-tiibe, and, on top of this, rests the casein as a well- 
defined, white, C3dindrical mass ; and above the casein- 
column is a clear solution containing the milk-solids 
other than fat and casein. It is absolutely necessary 
to allow the tubes to stand at least lo minutes before 
reading- the results, because it requires about this 
amount of time for the casein mass to come to a con- 
stant volume after suddenly removing the effect of 
centrifugal force. The volume remains practically 
constant after standing 10 minutes, little or no 
change taking place at room temperature even in 24 
hours. 

Reading the results. — To read the percentage of 
casein, the testing-tube is held in a perpendicular posi- 
tion with the scale on a level with the eye. The points 
of the scale marking the highest and lowest limits of 
the casein cylinder or column are noted. The differ- 
ence between the two gives directly the percentage of 
casein in the milk. Readings of one-half of a divi- 
sion can be made, corresponding to o.io per cent, and 
somewhat closer under favorable conditions and with 
sufficient skill. In the original description of the test, 
the casein mass is repeatedly called a ''pellet." This is 
a misleading and inaccurate description, since, accord- 
ing to standard authorities, a pellet is a ''small, round 
ball,'' like small shot or homeopathic pills. A more 
accurate description is that of a short cylinder or 
cylindrical column. The planes of division between 
the solid casein mass and the solutions below and 
above it are usually flat and readily permit definite 
reading of results. In some cases, when the testing- 
tube is not perfectly centered during the operation 
of whirling, the flat surfaces of the casein cylinder 
may not be exactly parallel with the bottom of the 



444 SCIENCE AND PRACTICE OF CHEESE-MAKING 

tube ; under such circumstances, the readings should 
be taken only on the graduated side of the tube. 
Sometimes, when the shaking is too vigorous, a film, 
sharp in outline and clearly distinguishable, projects 
below the layer of casein proper. The space of such 
a film should not be included in the reading. 

Accuracy of results. — In the original report of the 
test, the results of analysis of the milks of i6 indi- 
vidual cows are given, varying in casein content, as 
determined by the official chemical method, from 1.88 
to 3.65. The centrifugal method gives results which 
agree in most cases within o.io per cent of those of 
the official method. The greatest difference is 0.20 
per cent. These results represent the work of those 
skilled in handling the test. 

Special precautions. — In performing the opera- 
tions involved in the test, the following points must 
be most carefully observed : 

(i) If possible, use for testing only fresh milk 
containing no preservative. It is possible to get re- 
sults with milk which has been preserved by the use 
of one tablet of potassium bi-chromate in 300 cc. of 
milk, provided the test is made within four days ; 
after that time the flat surfaces of the casein column 
are apt to be broken up and irregular. 

(2) Milk should not contain more than 0.35 per 
cent acidity. In no case can curdled milks be used. 

(3) Tests should always be made in duplicate and 
only on representative samples of milk. 

(4) The dilute solution of acetic acid used must 
contain about 0.25 per cent ; if much weaker, the 
casein is not completely precipitated ; if considerably 
stronger, some of the casein may be dissolved. 



TESTS USED IN CHEESE-MAKING 445 

(5) At the time of mixing and during the test, 
the temperature of the acid solution and of the milk 
should not be lower than 65° nor higher than 75° F. ; 
the best temperature is 70° F. 

(6) In mixing milk, acid and chloroform, do not 
shake less than 15 seconds nor more than 20 seconds, 
and do not shake too hard. 

(7) After mixing, do not allow the mixture to 
stand more than 30 minutes before putting in tester. 

(8) Run the centrifuge at a speed of 2,000 revolu- 
tions a minute for 7^ or 8 minutes, the diameter of 
the revolving circle being 15 inches. 

(9) Allow the testing-tubes to stand in an up- 
right position 10 minutes at least before reading the 
percentage of casein. 

(10) Do not allow temperature of contents of 
testing-tube at any time to get far from the limits 
of 65° to 75° F. 

(11) The upper and lower surfaces of the cylin- 
drical column of solid casein must be perfectly flat 
and not ragged or broken up. 

Conditions affecting accuracy of results. — The 

following are among the conditions that render the 
results of the test inaccurate : 
(i) The use of sour milk. 

(2) The use of milk containing such preservatives 
as formaldehyd, chloroform, toluol or corrosive sub- 
limate. 

(3) The use of milk containing potassium bi- 
chromate, unless tested within four days. 

(4) Too strong or too dilute solution of acetic 
acid. 

(5) Poor quality of chloroform. 



44^ SCIENCE AND PRACTICE OF CHEESE-MAKING 

(6) A temperature of acid and milk below 65° or 
above 75° F. 

(7) Shaking mixture of acid, chloroform and milk 
too short a time, too long a time or too hard. 

(8) Allowing shaken mixture to stand too long 
before whirling. 

(9) Running the centrifuge at a speed below 1,950 
or above 2,050 revolutions a minute. 

(10) The use of a revolving wheel in the centri- 
fuge greater or less than 15 inches without a corre- 
sponding change in the number of revo'lutions. 

(11) Reading the results in less than 10 minutes 
after completion of whirling. 

(12) Allowing the temperature of the mixture to 
exceed the limits of 65° to 75° F. 

(13) Any condition which disturbs the distinct 
flatness of the upper or lower surface of the cylindri- 
cal column of solid casein. 



CHAPTER XXIX 

Cheese-Factory Management 

STATEMENT FOR PATRONS 

Whenever a dividend is made, each patron should 
receive with the dividend a statement containing all 
necessary items, which will enable each patron to 
calculate the dividend and satisfy himself that no 
errors have been made. It is convenient to use a 
printed blank form for making such statements to 
patrons. The form given below is suggested as cov- 
ering all important points, but one much simpler may 
usually answer the purpose. It is also highly de- 
sirable that a general statement be issued at the close 
of the season, giving a summary of the whole season's 
work. 

Statement of Cheese- 
Factory. 

1. Name of patron ....: 

2. Statement for month of (or whatever the period of time is) 19.... 

3. Sales include dates from to 

4. Number of pounds of cheese in sale (or sales) 

5. Number of pounds of milk represented in sale (or sales) 

6. Amount of money received $ 

7. Price received per pound for cheese (at each sale, and average if more 

than one) cents 

8. Expenses deducted $ 

9. Balance for dividends $ 

10. Net value of one pound of milk (weight-of-milk basis) cents 

11. Number of pounds of milk delivered by you 

12. Value of milk delivered by you $ 

13. Total number of pounds of milk-fat represented in sale (when fat 

basis is used) 

14. Average percent of milk-fat in milk per cent 

15. Net value of one pound of milk-fat cents 

447 



448 SCIENCE AND PRACTICE OF CHEESE-MAKING 



16 Average per cent of milk fat in milk delivered by you 

17. Number of pounds of milk fat delivered by you 

18. Value of milk-fat delivered by you 

19. Debtor by pounds of cheese at cents per pound. 

20. Money due you 

21. Number of pounds of cheese made from 100 pounds of milk 

22. Number of pounds of milk required to make one pound of cheese 

23- Number of pounds of cheese" made for one pound of fat in milk , 



BUSINESS MANAGEMENT OR ORGANIZA- 
TION OF A CHEESE-FACTORY 

The business management of a cheese-factory is 
g-enerally carried on according to one of two sys- 
tems ; in one case the ownership of the factory is 
private, while, in the other, it is vested in a stock 
company. 

In the case of private ownership of the cheese- 
factory, the owner receives a certain price per 
pound for making the cheese and is responsible 
for all expenses connected with the operations of 
cheese-making. The milk and cheese are regarded 
as the property of the patrons and they have some 
organized arrangement for selling the cheese and 
distributing the money. In some cases where the 
ownership of the factory is private, the milk is 
contracted for at a certain price and then the 
patrons have nothing to do with the business man- 
agement. 

When a cheese-factory is owned by a stock-com- 
pany, the patrons are the stockholders. They form a 
definite organization and through chosen officers carry 
on the entire business management from the hiring of 
a cheese-maker to the sale of the cheese. 

Preliminary steps in establishing a co-operative 
cheese-factory. — When a community is considering 
the question of organizing a stock-company for the 



CHEESE-FACTORY ORGANIZATION 449 

purpose of building and running a cheese-factory, 
the first point to be ascertained is the number of 
cows wliich can be utiHzed as a source of milk sup- 
ply. This information can be gained only by a 
careful personal canvass. In general, it may be 
said that no attempt should be made to establish 
a factory unless at least 150 cows within a radius 
of 3 or 4 miles can be relied upon to furnish milk. 
Dairymen should be on their guard against so- 
called factory "sharks," a name applied to repre- 
sentatives of supply houses who make a business 
of promoting co-operative factories and creameries. 
The promoter makes exaggerated representations 
of the profits of cheese-making for dairymen with- 
out reference to the number of available cows. 
When he is successful in persuading farmers to 
organize a company, he attends to the building and 
equipment, turning over the plant to the farmers at 
a price which nets him one to two thousand dollars. 
Before erecting a cheese-factory, inquiry for plans 
and cost should be made of the state department of 
agriculture or of the nearest agricultural college. 
In general, it will be found safe and profitable to 
have nothing whatever to do with any traveling 
agents. 

Formation of a cheese-factory company or as- 
sociation. — After a successful canvass has been 
made and there have been obtained signed agree- 
ments to furnish milk from a certain number of 
cows, on the part of those who intend to join the 
association, a meeting should be called for organi- 
zation. The money may be raised either by indi- 
vidual pledges to purchase a certain number of 



450 SCIENCE AND PRACTICE OF CHEESE-MAKING 

shares of stock at a certain price ; or an elected board 
of directors may be authorized to borrow the amount 
of money needed, the debt being discharged by taking 
a fixed proportion from the dividends of the associa- 
tion members. 

Articles of agreement or constitution and by- 
laws. — When it has been decided to form a cheese- 
factory association, it is necessary to prepare an 
agreement to be signed by all the members ; this 
agreement embodies the details of organization, 
usually in the form of a constitution and by-laws. 
Different conditions will call for differences in the 
details of such an agreement. Suggestions can be 
given here, but they will need modification and 
adaptation to suit the conditions peculiar to each 
association. 

(i) Name and object. — This association shall 

be known as the Cheese-Factory 

Co-operative Company; its object is to manufac- 
ture cheese from normal (whole) milk. The 
undersigned agree to become members of said com- 
pany. 

(2) Capital stock. — The capital stock of the com- 
pany shall be $ , divided into 

shares of $ each. 

(3) Officers. — The offfcers of the company shall 
be a president, a secretary and a treasurer, and 
these, with three other members of the company, 
shall constitute a board of directors. These offt- 
cers shall be elected by ballot at the annual meet- 
ing and shall hold office one year or until their 
successors have been elected and qualified. Vacan- 
cies in the board may be filled by the directors 



CHEESE-FACTORY ORGANIZATION 45I 

for the time ensuing until the next annual election. 
(4) Duties of officers. — (i) The president 
shall preside at all meetings of the company and 
of the board; in his absence, some other member 
of the board shall preside. He shall perform such 
other duties as may be indicated. All documents, 
drafts, etc., involving the interests of the com- 
pany, shall be signed by the president. He shall 
call special meetings when necessary. (2) The 
secretary shall keep an accurate record of all pro- 
ceedings of the meetings of the company and of 
the board. He shall issue notices of meetings, ap- 
pointments on committees, statements to patrons, 
etc. ; he shall sign all papers, carry on the cor- 
respondence, etc. (3) The treasurer shall receive 
and disburse the money of the company. He shall 
give receipt for all money belonging to the asso- 
ciation. He shall make out dividends, etc. He 
shall pay out money only upon orders signed by 
the president and secretary. He shall keep a cor- 
rect financial account between the company and 
its members. He shall keep a proper set of books, 
which shall be open for inspection to members of 

the company. He shall give bonds for $ 

(4) The board of directors shall elect one of their 
number as general business manager of the com- 
pany, who shall be responsible for the conduct of 
the business details of the company. The board 
shall appoint any needed agents, manage the com- 
pany's investments, audit all accounts and fix com- 
pensation for services in all cases. They shall make 
regulations and enforce them. They shall arrange 
for the keeping of a record of all necessary details, 



452 SCIENCE AND PRACTICE OF CHEESE-MAKING 

such as weights of milk deHvered daily by each 
member, fat-test of the same, the amounts of cheese 
made day by day, the sales of cheese, current ex- 
penses, etc. They shall distribute monthly among 
the members or patrons the money due them. 
They shall make a complete statement at the annual 
meeting covering for the year all matters relating to 
the business of the company. Meetings of the board 
may be called by the president or by any two of its 
members. 

(5) Meetings. — The regular annual meetings of 
the company shall be held on the first Tuesday of 
the month of Special meet- 
ings may be called by the president or on written 
request of ten members of the company. Written 
notices for all special meetings must be sent to 
each member of the company three days in advance 
of such meeting. In addition to the election of 
officers and presentation of reports, the members 
shall decide by majority vote at the annual meeting 
in what manner the dividends shall be made (weight- 
of-milk, fat-basis, etc.). 

(6) Regulations. — The following are samples of 
what regulations may be made: (a) The price for 

making cheese shall be cents a pound. 

(b) Members shall be held responsible for furnish- 
ing milk from the number of cows promised, (c) 
The cheese-maker may reject such milk as is 
tainted or of too high acidity or is any way un- 
suited to make high-grade cheese, (d) Milk must 
not be received unless it has been properly strained 
and delivered at the factory at a temperature not 
above degrees F. (e) The milk of each 



CHEESE-FACTORY ORGANIZATION 453 

patrons shall be tested for its percentage of fat not 
less often than once in lo days, (f) A testing-com- 
mittee consisting of the secretary or treasurer, one 
other director and one member not an officer shall 
assist the cheese-maker in testing the milk, (g) A 
patron's premises may be inspected by order of 
the board to ascertain the suitability of the conditions 
for producing and caring for clean milk. The board 
may order samples of milk taken ,at patron's farm 
when desired, (h) No patron shall, in any manner, 
adulterate milk to be taken to the factory, as by water- 
ing, skimming, addition of preservative, etc. No 

patron shall take more than pounds of whey for 

100 pounds of milk delivered. 

(7) Voting pozver. — Members may, at all meet- 
ings of the company, be entitled to one vote for each 
1,000 pounds of milk furnished by him during the 
preceding season or during the preceding portion of 
the current season, as shown by the records ; or each 
may have one vote for each share of stock owned by 
him. 

(8) Amendments. — Any changes or amendments 
to the constitution or by-laws may be made in writing 
and posted conspicuously in the cheese-factory one 
month previous to action upon them. Two-thirds vote 
of the stockholders is required to make such changes. 



CHAPTER XXX 

The Literature of Cheese-Making 

It is desirable to give references to the literature 
of cheese-making for the benefit of those who wish 
to go to original sources of information. In pre- 
paring the list given below, the aim is mainly to 
cover the ground represented In the subject-matter 
of the book. A selection has been made of what 
may be regarded as the most useful material for 
this purpose, no attempt being made to present 
an exhaustive list of everything written on the 
subject. 

In order to render the material most readily 
available for reference, the following plan is 
adopted : There is first given a continuously 
numbered list of the publications referred to; the 
arrangement is, first, by institutions and then 
under each the individual articles are given in 
chronological order. Then follows an index of 
the subjects treated in this list of publications. 
It is believed that this plan will prove the most 
useful in enabling anyone to consult the literature. 

PUBLICATIONS RELATING TO CHEESE-MAKING 
Cornell University Experiment Station, Ithaca, N. Y. 

1 1st Ann. Rept. (1879-80). Experiments upon the cur- 
ing of cheese (pp. 9-27). Babcock. 

2 Bui. 85 (March, 1895). Whe3^-butter. Wing. 

3 Bui. 158 (Jan., 1899). Sources of gas and taint- 
producing bacteria. Moore and Ward. 

4 Bui. 178 (Jan., 1900). The invasion of the udder by 
bacteria. Ward. 

5 Bui. 203 (July, 1902). The care and handling of 
milk. Hunziker. 

454 



THE LITERATURE OF CHEESE-MAKING 455 

Iowa Agricultural College Experiment Station, Ames, Iowa 

6 Bui. 21 (1893). Investigations in cheese -making 
(pp. 751-767). Wallace. 

7 Bui. 24 (1894). Changes during cheese -ripening (pp. 
969-984). Patrick. 

8 Bui. 57 (1901). Experiments in curing cheese. 
McKay. 

Michigan State Agricultural College Experiment Station, 
East Lansing, Mich. 

9 Special Bui. 16 (June, 1902). Aeration of milk. 
Marshall. 

10 Special Bui. 21 (Sept., 1903). Cheese problems: 

(a) Relation of yield of cheese and per cent of fat in milk. 

(b) Paraffining cheese, (c) Cheddar vs. stirred curd, (d) 
Cheese-ripening as afifected by temperature and moisture. 
{e) Sage cheese, (f) Gassy milk. Michels. 

11 Special Bui. 23 (Jan., 1904). A preliminary note on 
the associative action of bacteria in the souring of milk and 
in other milk fermentations. Marshall. 

12 Special Bui. 29 (May, 1904). Additional work upon 
the associative action of bacteria in the souring of milk and 
in other milk fermentations. Marshall. 

13 Special Bui. 2>2> (June, 1905). Extended studies of 
the associative action of bacteria in the souring of milk. 
Marshall. 

14 Special Bui. 42 (March, 1908). Bacterial associa- 
tions in the souring of milk. Marshall. 

15 Bui. 183 (June, 1900). Gassy curd and cheese. 
Marshall. 

16 Bui. 201 (June, 1902). Aeration of milk. Marshall. 

Minnesota Agricultural Experiment Station, St. Anthony Park, 

Minnesota 

17 Bui. 19 (Jan., 1892). Experiments in cheese-mak- 
ing. Incorporating cream into cheese (pp. 20-25). Snyder. 

18 Bui. 27 (Feb., 1893). Losses of milk-solids in cheese- 
making (pp. 57-62). Snyder. 

19 Bui. 35 (Oct., 1894). Manufacture of sweet-curd 
cheese. Haecker. 

New York Agricultural Experiment Station, Geneva, N. Y. 

20 Bui. 37 (Nov., 1891) and 10th Ann. Rept. (pp. 220- 
299). Investigation of cheese : (a) Experiments in the manu- 
facture of cheese. (6) Influence of composition of milk on 
composition and yield of cheese, (c) A study of the process 
of ripening of cheese. Van Slyke. 



45^ SCIENCE AND PRACTICE OF CHEESE-MAKING 

21 Bui. 43 (June, 1892). Experiments in the manu- 
facture of cheese during May. Van Slyke. 

22 Bui. 45 (Aug., 1892). Experiments in the manu- 
facture of cheese during June. Van Slyke. 

23 Bui. 46 (Sept., 1892). Experiments in the manu- 
facture of cheese during July and August. Van Slyke. 

24 Bui. 47 (Nov., 1892). Experiments in the manu- 
facture of cheese during September and October. Van Slyke. 

25 Bui. 50 (Jan., 1893) and 11th Ann. Rept. (pp. 299- 
467). Summary of the results of experiments made in the 
manufacture of cheese during the season of 1892. Van Slyke 

26 Bui. 54 (May, 1893) and 12th Ann. Rept. (pp. 276 
319). Experiments in the manufacture of cheese: Part 1 
Manufacture of cheese from normal milk rich in fat. Part IT, 
Study of cheese-ripening process. Van Slyke. 

27 Bui. 56 (May, 1893) and 12th Ann. Rept. (pp. 244- 
275). Experiments in the manufacture of cheese: Part I, 
The manufacture of Edam cheese. Part II, The manufacture 
of Gouda cheese. Van Slyke. 

28 Bui. 60 (Oct., 1893). Investigation relating to the- 
manufacture of cheese. Part I, Results of work done in the 
No. 1 factory of E. L. Stone at Mannsville, Jefferson Co., 
during the season of 1893. Van Slyke. 

29 Bui. 61 (Nov., 1893). Investigation relating to the 
manufacture of cheese. Part II, Results of work done in the 
factory of G. Merry at Verona, Oneida Co., N. Y., during the 
season of 1893. Van Slyke. 

30 Bui. 62 (Dec, 1893). Investigation relating to the 
manufacture of cheese. Part III, Results of Work done 
during the season of 1893 in 48 different factories, located 
in 8 different counties. Van Slyke. 

31 Bui. 65 (Jan., 1894) and 12th Ann. Rept. (pp. 319- 
486). Investigation relating to the manufacture of cheese. 
Part IV, Summary of the results of work done in cheese- 
factories during the seasons of 1892-3. Van Slyke. 

32 Bui. 68 (March, 1894). Investigation relating to 
the manufacture of cheese. Part V, Fat in milk as a practical 
basis for determining the value of milk for cheese -making. 
Van Slyke. 

33 Bui. 71 (May, 1894). Some reasons why there 
should be a legal standard for cheese ir_ New York state. 
Van Slyke. 

34 Bui. 79 (Nov., 1894) and 13th Ann. Rept. (pp. 351- 
379). Comparison of different breeds of cattle. The cost of 
cheese production^ Van Slyka. 



THE LITERATURE OF CHEESE-MAKING 457 

35 Bui. 82 (Dec, 1894) and 13th Ann. Rept. (pp. 452- 
522). Results of investigation relating to the manufacture 
of cheese for the season of 1894. Van Slyke. 

36 Bui. 105 (Aug., 1896) and 15th Ann. Rept. (pp. 37- 
65). Effects of drouth upon milk and cheese production. 
Van Slyke. 

37 Bui. 110 (Oct., 1896) and 15th Ann. Rept. (pp. 66- 
106). Milk-fat and cheese yield. Van Slyke. 

38 Bui. 183 (Dec, 1900) and 19th Ann. Rept. (pp. 29- 
51). Notes on some dairy troubles: (a) Flavor in milk and 
its products, {b) Fishy flavor in milk, (c) Bitter flavor in 
Neufchatel cheese. (d) Sweet flavor in cheddar cheese. 
{e) Rusty spot in cheddar cheese. Harding, Rogers and 
Smith. 

39 Bui. 184 (Dec, 1900) and 19th Ann. Rept. (pp. 251- 
260). The influence of the temperature of curing upon the 
commercial quality of cheese. Smith. 

40 Bui. 203 (Dec, 1901) and 20th Ann. Rept. (pp. 165- 
193). A study of enzyms in cheese. Van Slyke, Harding 
and Hart. 

41 Bui. 207 (Dec, 1901) and 20th Ann. Rept. (pp. 
194-219). Conditions affecting weight lost by cheese in cur- 
ing. Van Slyke. 

42 Bui. 225 (Dec, 1902) and 21st Ann. Rept. (pp. 27- 
53). Control of rusty spot in cheese-factories. Harding and 
Smith . 

43 Bui. 231 (Feb., 1903) and 22d Ann. Rept. (pp. 165- 
187). The relation of carbon dioxid to proteolysis in the 
ripening of cheddar cheese. Van Slyke and Hart. 

44 Bui. 233 (June, 1903) and 22d Ann. Rept. (pp. 188- 
217). Rennet enzym as a factor in cheese-ripening. Van 
Slyke, Harding and Hart. 

45 Bui. 234 (July, 1903) and 22d Ann. Rept. (pp. 218- 
242). Experiments in curing cheese at different tempera- 
tures. Van Slyke, Smith and Hart. 

46 Bui. 236 (July, 1903) and 22d Ann. Rept. (pp. 243- 
273). Conditions affecting chemical changes in cb >ese- 
ripening. Van Slyke and Hart. 

47 Bui. 261 (Jan., 1905) and 24th Ann. Rept. (pp. 238- 
271). Some of the relations of casein and paracasein to bases 
and acids and their application to cheddar cheese. Van 

jl'vkc Cfwd li Q-Tt 

48 Technical Bui. 3 (Dec, 1906) and 25th Ann. Rept. 
(pp. 203-286). I, The action of dilute acids upon casein 
when no soluble compounds are formed. II, The hydrolysis 
of the sodium salts of casein. Van Slyke (L. L.) and Van 
Slyke {D. D.). 



45^ SCIENCE AND PRACTICE OF CHEESE-MAKING 

49 Technical Bui. 4 (April, 1907). I, Some of the first 
chemical changes in cheddar cheese. II, The acidity of the 
water-extract of cheddar cheese. Van Slyke and Bosworth. 

50 Technical Bui. 6 (Dec, 1907). Chloroform as an 
aid in the study ol milk-enzyms. Harding and Van Slyke. 

Oregon Agricultural Experiment Station, Cornwallis, Ore. 

51 Bui. 78 (March, 1904). Canning cheese. Pernot. 

U. S. Department of Agriculture, Bureau of Animal Industry, 
Dairy Division, Washington, D. C. 

52 Bui. 11 (Nov., 1895) and 55 (Feb., 1903). Statistics 
of the dairy. Alvord. 

53 Bui. 15 (Oct., 1896). The cheese industry of the 
state of New York. Gilbert. 

54 Bui. 17 (Nov., 1896). Dairy schools. Pearson. 

55 Bui. 49 (June, 1903). The cold-curing of cheese. 
Report upon experiments conducted under the auspices of 
the U. S. Department of Agriculture, Bureau of Animal In- 
dustry, Dairy Division, in co-operation with the Wisconsin 
Agricultural Experiment Station and the New York Agri- 
cultural Experiment Station. Alvord. 

56 Bui. 62 (July, 1904). The relation of bacteria to 
the flavors of cheddar cheese. Rogers. 

57 Bui. 75 (Sept., 1905). Records of dairy cows in the 
United States. Lane. 

58 Bui. 83 (March, 1906). The cold storage of cheese. 
Lane. 

59 Bui. 85 (May, 1906). The cold-curing of American 
cfieese. Doane. 

60 Bui. 105 (Jan., 1908). Varieties of cheese: descrip- 
tions and analyses. Doane and Lawson. 

61 Bui. 110 (Nov. 1908). Development of lactic acid 
in cheddar cheese-making. Doane. 

Utah Agricultural Experiment Station, Logan, Utah 

62 Bui. 73 (Aug., 1901). Experiments in cheese-mak- 
ing (pp. 41-54). Linjield. 

63 Bui. 96 (March, 1906). Canning cheese. Paraffining 
cheese (pp. 128-132). Clark and Crockett. 

Vermont Agricultural Experiment Station, Burlington, Vt. 

64 5th Ann. Rept. (1891). (a) Making cheese from 
different qualities of milk (pp. 88-95). (b) Losses in cheese- 
making (pp. 95-100). Cooke and Hills. 



THE LITERATURE OF CHEESE-MAKING 459 

Wisconsin Agricultural Experiment Station, Madison, Wis. 

65 8th Ann. Rept. (1891). The feeding vahie of whey 
(pp. 38-48). Henry. 

66 11th Ann. Rept. (1894). (a) Influence of fat upon 
yield of cheese (pp. 131-134). {h) Influence of fat on qualit}^ 
of cheese (pp. 134-137). (c) Yield of cheese in factories from 
different qualities of milk and at different seasons (pp. 137- 
144). {d) Loss in curing cheese (pp. 145-146). {e) Cleaning 
milk with a centrifugal cream-separator for cheese production 
(pp. 146-149). Babcock. 

(/) Sources of bacterial contamination of milk (pp. 150- 
165). Russell. 

(g) Effect of salt upon cheese (pp. 220-222). Decker. 

67 12th Ann. Rept. (1895). \a) The centrifugal sepa- 
ration of casein and insoluble phosphates from milk (pp. 
93-99). (6) Relation between yields of milk-solids and cheese 
(pp. 100-120). (c) Relation between specific gravity and 
solids of milk (pp. 120-126). {d) Hot iron test (pp. 133-134). 
{e) Albumen cheese (pp. 134-136). Babcock. 

(/) Effect of aeration on flavor of tainted curds in cheese- 
making (pp. 127-129). (g) Gas-producing bacteria and their 
relation to cheese (pp. 139-150). RusscU. 

Qi) Influence of acid on texture of cheese (pp. 129-133). 
Russell and Decker. 

(i) Ripening milk before setting (pp. 136-138). Decker. 

68 13th Ann. Rept. (1896). (a) Rise and fall of bac- 
teria in Cheddar cheese (pp. 95-111). (b) Pure lactic acid 
cultures in cheese-making (pp. 112-126). Russell. 

(c) Moisture supply in cheese-curing rooms (pp. 156- 
163). Decker. 

69 14th Ann. Rept. (1897). (a) Unorganized ferments 
of milk: a new factor in the ripening of cheese (pp. 161-193). 
(6) Influence of temperature on the ripening of cheese (pp. 
194-210). Babcock and Russell. 

70 Bui. 60 (May, 1897). The cheese industry: its de- 
velopment and possibilities in Wisconsin. Babcock and Rus- 
sell. 

71 Bui. 61 (Sept., 1897). The constitution of milk with 
especial reference to cheese-production. Babcock. 

72 Bui. 62 (Sept., 1897). Tainted or defective milks. 
Their causes and methods of prevention. Russell. 

73 15th Ann. Rept. (1898). (a) Effect of varying 
strengths of rennet in curdling milk (pp. 31-34). (6) Action 
of rennet in watered milk (pp. 35-36). (c) Action of common 
salt on rennet action (pp. 37-41). (d) Methods of handling 
sour milk in making cheese (pp. 42-44). Decker 



400 SCIENCE AND PRACTICE OF CHEESE-MAKING 

(c) Improved curd test for detection of tainted milks 
(pp. 45-53). Babcock, Russell and Decker. 

(/) Properties of galactase, a digestive ferment of milk 
(pp. 77-87). (g) Distribution of galactase in cow's milk 
(pp. 87-92), Babcock, Russell and Vivian. 

{h) Relative absorption of odors in warm and cold milk 
(pp. 104-109). Russell. 

74 16th Ann. Rept. (1899). (a) Coating cheese with 
paraffin (pp. 153-155). Decker. 

{b) Action of proteolytic ferments on milk with special 
reference to galactase, the cheese-ripening enzym (pp. 155- 
174). Babcock, Russell and Vivian. 

(c) Effect of digesting bacteria on cheese-solids (pp. 
187-193). Russell and Bassett. 

75 17th Ann. Rept. (1900). Influence of rennet on 
cheese-ripening (pp. 102-122). Babcock, Russell and Vivian. 

76 18th Ann. Rept. (1901). (a) Print cheese (pp. 132- 
135). Farrington. 

(6) Influence of cold-curing on quality of cheese (pp. 
136-161). Babcock, Russell, Vivian and Baer. 

{c) Influence of sugar on nature of fermentation in 
milk and cheese (pp. 162-176). Babcock, Russell, Vivian and 
Hastings. 

77 19th Ann. Rept. (1902). (a) Influence of cold- 
curing on quality of Cheddar cheese (pp. 150-164). (6) Influ- 
ence of temperature approaching 60°F. on development of 
flavor in cold-cured cheese (pp. 165-173). (c) Influence of 
varying quantities of rennet on cold-cured cheese (pp. 174- 
179). {d) Conditions affecting development of white specks 
in cold-cured cheese (180-184). Babcock, Russell, Vivian and 
Baer. 

78 Bui. 94 (Aug., 1902). Ctiring of cheddar cheese 
with reference to cold-curing. Consolidated cheese-curing 
stations. Babcock and Russell. 

79 Bui. 101 (July, 1903). Shrinkage of cold-cured 
cheese during ripening. Experiments in paraffining cheese. 
Babcock, Russell and Baer. 

80 21st Ann. Rept. (1904). (a) Relation of flavor de- 
velopment in cold-cured cheddar cheese to bacterial life in 
same (pp. 155-163). Russell and Hastings. 

81 Bui. 115 (Sept., 1904). The quality of cheese as 
affected by rape and other green forage plants fed to dairy 
cows. Baer and Carlyle. 

82 2 2d Ann. Rept. (1905). (a) The Swiss cheese in- 
dustry of Wisconsin; whey butter-making (pp. 157-180). 
Farrington. 



THE LITERATURE OF CHEESE-MAKING 461 

(b) Lactose-fermenting yeasts, the cause of abnormal 
fermentation in Swiss cheese (pp. 207-221). Hastings. 

83 Bui. 128 (Sept., 1905). A Swiss cheese trouble 
caused by a gas-forming yeast. Russell and Hastings. 

84 Bui. 132 (Dec, 1905). The manufacture of whey- 
butter at cheese-factories. Farrington. 

85 23d Ann. Rept. (1906). (a) Development of factory 
dairying in Wisconsin (pp. 100-106). Russell and Baer. 

(6) Distribution of lactose-fermenting yeasts in dairy 
products (pp. 107-115). Hastings. 

86 24th Ann. Rept. (1907). (a) Influence of metals on 
the action of rennet (pp. 134-159). Olson. 

(h) Analyses of old cheese, skim-milk cheese, etc. (pp. 
160-170). Woll and Olson. 

87 Bui. 162 (April, 1908). Rusty cans and their effect 
upon milk for cheese-making. Olson. 

Dominion of Canada Dairy Commission, Department of 
Agriculture, Ottawa, Can. 

88 2d Ann. Rept. (1891-2). Experimental cheese-mak- 
ing (pp. 146-153). Robertson and Ruddick. 

89 3d Ann. Rept. (1892-3). Experiments in cheese- 
making (pp. 214-219). Robertson and Ruddick. 

90 Rept. Conference Dairy Instructors and Experts 
(1903). The cool-curing of cheese (pp. 96-110). Ruddick. 

91 Rept. of Dairy Com'r (1906). (a) Cool-cured cheese 
(pp. 8-9). (6) Management of a cool curing-room (pp. 13-14). 
(c) Coating cheese with paraffin (pp. 14-15). Ruddick. 

92 Rept. of Dairy Com'r (1907). (a) The cheese indus- 
try (pp. 8-17). (Jd) Cool -cured cheese (pp. 17-18). Ruddick. 

Ontario Agricultural College, Guelph, Ontario, Canada 

93 Buls. 95 and 96 (1894) and 20th Ann. Rept. (1894). 
(a) The composition of milk, whey and cheese in relation to 
one another (pp. 20-33). Shuttleworth. 

(b) Experiments in cheese-making (pp. 134-141). Dean. 

94 Bui. 102 (May, 1896) and 22d Ann. Rept. (1896), 
(pp. 41-56). Experiments in cheese-making. Dean. 

95 23d Ann. Rept. (1897). (a) Experiments in cheese- 
making (pp. 41-59). Dean. 

(b) Bad flavor in cheese caused by undesirable bacteria 
in water used in factory (pp. 141-144). Harrison. 

96 24th Ann. Rept. (1898). Experiments in cheese- 
making (pp. 40-64). Dean. 

97 25th Ann. Rept (1899) Experiments in cjheese- 
making (pp. 54-65). Dean. 



462 SCIENCE AND PRACTICE OF CHEESE-MAKING 

98 26th Ann. Rept. (1900). Experiments in cheese- 
making (pp. 37-44). Dean. 

99 27th Ann. Rept. (1901). Experiments in cheese- 
making (pp. 44-55). Dean. 

100 28th Ann. Rept. (1902). (a) Experiments in 
cheese-making (pp. 64-68). Dean. 

(b) Investigations regarding the ripening of cheese (pp. 
40-41). Harcourt. 

101 Bui. 120 (May, 1902). Bitter milk and cheese. 
Harrison. 

102 Bui. 121 (June, 1902). Ripening of cheese in cold 
storage compared with ripening in ordinary curing-rooms. 
Dean, Harrison and Harcourt. 

103 29th Ann. Rept. (1903). Experiments in cheese- 
making (pp. 60-76). Dean. 

104 Bui. 130 (Dec, 1903). Bacterial contents of cheese 
cured at different temperatures. Harrison and Connell. 

105 Bui. 131 (Dec, 1903). Ripening of cheese in cold- 
storage versus ordinary curing-rooms. Dean and Harcourt. 

106 30th Ann. Rept. (1904). Experiments in cheese- 
making (pp. 74-81). Dean. 

107 31st Ann. Rept. (1905). Experiments in cheese- 
making (pp. 115-126). Dean. 

108 Bui. 141 (April, 1905). Gas-producing bacteria 
and their effect on milk and its products. Harrison. 

109 32d Ann. Rept. (1906). Experiments in cheese- 
making (pp. 108-119). Dean. 



Index to Literature of Cheese-Making 

The reference numbers below indicate the serial 
numbers (in heavy type) in the preceding list of publi- 
cations, which go from i to 109. 

Acidity of water-extract of cheese 20, 49 

effect on texture of cheese 67 

Acid, lactic, development of, in cheese-making 61 

pure cultures in cheese-making 68 

milk, handling of, in cheese-making 73 

Acids, action upon casein 48 

adsorption by casein 48 

effect of, on enzyms in cheese 40, 44, 75, 77 

effect of, on galactase in cheese-ripening 40, 74 

effect of, on rennet in cheese-ripening. . . .'. .44, 75, 77 

phosphates in cheese 49 

relations to cheese-ripening 40, 44, 46 

Adsorption of acids by casein 48 

Aeration of milk 9, 16, 24, 25, 66 

of milk by dipping 24 

of milk by centrifugal separator 24, 66 

Albumen cheese 67 

Albumin in cheese 20-35 

in milk 20-35 

in whey 20-3 5 

lost in cheese-making 20-35 

relations of, to casein in milk 20-35 

Amino acids in cheese 40, 43, 46, 74-75, 77 

Ammonia in cheese 40, 43, 46, 74-75, 77 

Analyses of cheese , 20-35, 40, 44-46, 49, 60, 75 

of milk 20-35 

of whey 20-35 

Bacteria, associative in souring of milk 11-14 

digesting and cheese-solids 74 

in udder 4, 40 

producing gas and taints in cheese, 3, 10, 15, 67, 108 

producing rust -red spots in cheese 38, 42 

relation of, to cheddar-cheese flavors. . . .36, 67, 72 

rise and fall of, in cheddar cheese 68 

Bacterial contamination of milk 66 

content of cheese kept at different temperatures, 104 

463 



464 SCIENCE AND PRACTICE OF CHEESE-MAKING 

Bitter flavor in cheese and milk 46, 101 

Breeds of cattle, comparative value of, for cheese produc- 
tion 34 

Brine-soluble protein in cheese 40, 44-46, 49 

Butter -fat (see Fat). 

Butter, whey 2,132 

Canning cheese 51,63 

Casein, action of acids on 48 

action of rennet and pepsin on 44 

adsorption of acids by 48 

amount in cheese 20-35 

amount in milk 20-35 

amount in whey 20-35 

centrifugal separation of 67 

influence on composition of cheese 20-35 

influence on yield of cheese ". . .20-35 

lost in cheese-making 20-35 

market value of, in cheese 32, 67 

relation to albumin in milk 20-35 

relation to fat in milk 20-35 

relation to fat in skim-milk 20-25 

relation to fat in skim-milk cheese 20-25 

Centrifugal separation of casein from milk 67 

Cheddar and stirred -curd processes compared 10, 20-25 

Cheese, advantages of cold storage, 8, 10, 41, 45, 55, 58-59, 

69, 76-80, 90-92, 102, 105 

albumin in 20-3 5 

amino acids in 40, 43-46, 74-75, 77 

ammonia in 40, 43-46, 74-75, 77 

analyses of 6, 17, 20-35,40, 43-46,49, 77, 86 

canning of 51,63 

casein and albumin in 20-35 

central curing-room for 41, 78, 90-92 

cheddar and stirred-curd processes compared, 

10, 20-25 

chemical changes in ripening of 45-46 

chloroformed, changes in 40, 43-44 

cold-cured, 8, 10, 41, 45, 55, 58-59, 69, 76-80, 

90-92, 102, 105 

cold-cured, composition of 45 

cold-cured, white specks in 77 

comparative production of, by different breeds 

of dairy cattle 34 

composition of 20-35, 40, 43-46 

composition of, in relation to composition of milk, 

20-35 



INDEX TO LITERATURE OF CHEESE-MAKING 465 

Cheese — continued 

conditions used in manufacturing operations of, 20-35 

consolidated stations for curing 78 

cost of producing 34 

Edam, manufacture and composition of 19, 27 

effect of cold storage on moisture of, 45, 55, 58-59,' 

78-79, 90-92, 102,'l05 

effect of moisture on quality of 41, 45, 46 

effect of paraffining. .10, 45-46, 55, 58-59, 63, 79,' 91 
effect of temperature in ripening, 8, 10, 39, 41, 

45-46, 55, 58-59, 69, 76-80, 90-92, 102, 105 
experiments in manufacture of , 6, 10, 17, 19, 20-35, 
64, 67, n, 81-82, 88-89, 93-100, 103, 106-107, 109 

fat in 6, 10, 18, 20-35, 37, 64, 67, 93 

flavor and texture of, 20-25, 39, 45, 46, 56, 66-67, 

76-78, 80, 93 

gassy 3, 10, 15, 67, 108 

Gouda, manufacture and composition of 19, 27 

industry in New York 53 

industry in Wisconsin 70, 82, 85 

influence of milk on composition of 20-35 

influence of milk on yield of 20-35 

loss of fat in ripening of 41 

loss of water in ripening of, 41, 45, 55, 58-59, 66, 69, 

78-79, 90-92, 102, 105 
loss in weight in ripening of (see Loss of water). 

losses in making of 6, 10, 18, 20-35, 64, 93 

made from milk containing added cream, 

6, 10, 17, 20-25 

made from normal milk rich in fat 26 

made from skimmed milk 20-25 

market value increased by cold storage (see Cold 

storage). 

market value of casein and water in 32, 67 

milk required to make one pound of, 20-35, 66, 93-100 

paraffining of 10, 45-46, 55, 58-59, 63, 79, 91 

print 76 

production comparison of dairy breeds 34 

quality improved by cold storage (see Cheese, cold 

cured). 

quick ripening, conditions for 46 

rise and fall of bacteria in 68 

sage 10 

slow -ripening 46 

solids in 20-35 

soluble proteins in 40, 43-46, 74-75, 77 

sources of carbon dioxid in 43 



466 SCIENCE AND PRACTICE OF CHEESE-MAKING 

Cheese — continued 

stirred-curd, comparison with cheddar process, 

10, 20-25 
texture, relation of, to conditions of ripening, 

39, 45-46, 55, 58-59, 76-80, 90-92, 102, 105 

varieties of, descriptions and analyses 60 

water in 20-35 

yield and milk-fat 20-35, 66, 93 

Cheese-curd (see Curd). 

Cheese-factories, methods of paying for milk at, 

32, 64, 67, 90-92, 93 

Cheese-making, albumin lost in 20-35 

casein lost in 20-35 

cheddar process of 20-35 

effect of adding cream 20-25 

effect of adding skim-milk 20-25 

efifect of cutting curd hard and soft .... 20-35 
effect of exposing milk to foul odors. . . .24 

effect of shutting up milk in cans 24 

effect of tainted milk 23, 24, 73 

effect of using different amounts of rennet, 

20-25 

experiments in 6, 18, 20-25, 90-100 

fat lost in, 6, 18, 20-25, 64, 66, 67, 90, 92, 

93-100 

pure lactic acid cultures in 68 

Cheese-ripening, effect of moisture 10, 41, 45, 68 

effect of rennet 26, 44, 75,77 

effect of salt 46, 66 

effect of size 4 1 , 46 

effect of temperature, 8, 10, 41, 45-46, 55, 

58-59, 69, 76-80, 90-92, 102, 105 

use of hygrometer in 27, 68 

Chemical changes in cheese 46 

composition of cheese 20-25, 45-46 

composition of milk 20-25 

composition of whey 20-25 

Chloroformed cheese (see Cheese, chloroformed). 
Cold-cured cheese (see Cheese, cold-cured). 
Composition of cheese, milk and whey (see Chemical com- 
position). 
Cream, addition to normal milk in cheese-making, 

6, 10, 17, 20-25 
Curd, comparison of ordinary and high temperatures of 

heating 20-25 

cutting of 20-35 

effects of cutting coarse and line 20-25 



INDEX TO LITERATURE OF CHEESE-MAKING 467 

Ciird — continued 

effects of cutting hard and soft 20-25 

gassy 3, 10, 15, 67, 108 

heating and stirring 20-35 

temperature used in heating 20-35 

time from cutting to drawing whey 20-35 

Curd-test for detection of tainted milk 73 

Curing-rooms 27, 41, 45-46, 68, 78 

moisture supply in 27, 41, 68 

Dairy, statistics of 52 

cows, records of 75 

schools 54 

Drouth, effects of, on milk and cheese production 36 

Edam cheese, manufacture and composition of 19, 27 

Enzyms, action in cheese 40, 44, 74, 75 

effect of chloroform, ether and formalin on, 

40, 50, 73 

effect of acids on 40, 44, 73 

effect of heat on 40, 73 

eft'ect of salt on 40, 73 

galactase 40, 69, 73, 74 

in milk 40, 69, 73 

in rennet 40, 44, 75, 77 

Ether, effect of, on the action of enzyms 40, 74 

Factories (see Clieese-factories). 

Fat, amount in cheese 20-35 

amount in milk 20-35 

amount in whey 20-35 

amount lost and recovered in cheese-making 20-35 

in cheese, influence on ripening of cheese 41, 46 

in milk, relation of, to casein in cheese 20-35 

in milk, relation of, to fat in cheese 20-35 

in milk, relation of, to composition of cheese 20-35 

in milk, relation of, to yield of cheese 20-35 

in milk, relation to casein in milk 20-35 

in milk, relation to casein in skim-milk 20-25 

in milk, yield of cheese for each pound of 20-35 

Feeding value of whey 65 

Flavor of cheese 20-25 

bitter, in cheese and milk 46, 101 

relation of bacteria to cheddar cheese 36, 67, 102 

relation of conditions of ripening to, 39, 45-46, 55, 

58-59,^6-78, 90-92, 102, 105 

relation of yeasts to, in cheese 83, 108 

sweet, in cheese 38 

tainted, in milk and cheese 23-25, 72 

Foods affecting flavor of cheese 20-25, 81 



468 SCIENCE AND PRACTICE OF CHEESE-MAKING 



Gas-producing bacteria in curd and cheese. .3, 10, 15, 67, 108 

Gouda cheese, manufacture and composition of 19, 27 

Hot -iron test 67 

Lactation advancing, influence on casein and albumin in 

milk 20-35 

influence on cheese production. . .20-35 

influence on fat in milk 20-35 

influence on ratio of fat to casein, 20-35 

tactic acid, action on casein 48 

development of, in cheese-making 61 

pure cultures in cheese-making 68 

Loss of casein in cheese-making 20-25 

carbon dioxid in cheese-ripening 43 

fat in cheese-ripening 6, 10, 18, 20-35, 64, 93 

milk constituents in cheese-making, 6, 10, 18, 

20-35, 64, 93 

solids in cheese-ripening 26, 41 

water in cheese-ripening, 41, 45, 55, 58-59, 66, 69, 

78-79, 90-92, 102, 105 
weight in cheese-ripening (see Loss of water). 
Manufacture of cheese (see Cheese-making). 

Metals and rennet action 86 

Milk, absorbed odors in 38,73 

aeration of 9, 16, 24, 25, 66 

albumin in 20-35 

amount required for cheese 20-35, 66, 93 

analyses of (see Analyses). 

at cheese -factories, methods of paying for (see 
Cheese-fa ct ories) . 

average composition of 20-35 

care and handling of 5,16 

casein in (see Casein). 

cheese-producing constituents of 20-35 

coagulation by rennet 20-35 

composition of 20-35 

composition of , relation to composition of cheese . .20-35 
constituents lost in cheese-making (see Loss in cheese- 
making) . 
containing added cream, relation of fat to casein in, 

20-25 

effect of exposing foul odors on cheese-making 24 

effect of shutting up in cans 24 

enzyms (see Enzyms in milk), 
fat in (see Milk -fat). 

fermentation of sugar in 76 

flavors in 3, 10, 15, 20-25, 39, 67, 81, 108 



INDEX TO LITERATURE OF CHEESE-MAKING 469 

iVIilk — continued 

influence of composition of, on composition of cheese, 

20-35 
paying for, in cheese-making (see Cheese-factories). 

relation of albumin and casein in 20-35 

relation of casein and fat in 20-35 

required to make one pound of cheese. . . .20-35, 66, 93 

ripening before setting 67 

skimmed, relation of fat to casein in 20-25 

solids in 20-3 5 

sour, handling of, in cheese-making 73 

sugar in 20-3 5 

tainted 3, 10, 15, 20-25, 67, 72, 108 

Milks, difference in cheese-producing power of dift'erent, 

20-35, 71 

effect of adding cream to, in cheese-making 20-25 

effect of adding skim-milk to, in cheese-making. . 20-25 
effect of removing fat from, in cheese-making . ..20-25 

Milk-cans, rusty and rennet action 87 

Milk-fat, and cheese yield ._ 20-35, 66, 93 

as a basis for measuring cheese yield, 20-35, 66, 93 
as a basis of paying for milk at cheese-factories 
(see Cheese-factories). 

cheese from normal milk rich in 26 

cheese-producing power of 20-35 

effect of drouth on 36 

influence on composition of cheese 20-35 

influence on yield of cheese 20-35 

loss of, in cheese-making (see Loss of fat). 

relation to casein in milk 20-35 

relation to casein in skimmed milks 20-25 

yield of cheese for each pound of 20-25, 66, 93 

Milk-solids and cheese yield 20-35, 66 

cheese-producing 20-35 

in whey 20-35 

relation, specific gravity to 67 

New York State, cheese industry of 53 

Nitrogen compounds in cheese . . . .20-35, 40, 43-46, 49, 74-75 

in milk 20-35 

water-soluble in cheese, 20-35, 40, 

43-46, 49, 74-75 

Paracasein in cheese 20-35, 40. 43-46, 49 

Paraffin, effect of use on cheese, 10, 45-46, 55, 58-59, 63, 79, 91 

Paraffining, effect on market value of cheese, 45, 55, 58-59, 

^' 63, 79, 91 

Pepsin, commercial, action in cheese-ripening 44. 75 



470 SCIENCE AND PRACTICE OF CHEESE-MAKING 

Phosphates, acid m cheese 49 

sokible in cheese 49 

Products in cheese-ripening, cumulative and transient. . . .46 
QuaHty of cheese improved by cold storage (see Cheese, 
cold-cured). 

of cheese, influence of fat on 6, 17, 20-25, 66 

Rennet, action in cheese-ripening 26, 44, 46, 75, 77 

effect of metals on 86 

effect of rusty cans on 87 

effect of salt on 73 

effect of varying strength of, in coagulating 

milk 73 

effect of watered milk on 73 

Rennet -extra'ct, amount used in cheese-rnaking 20-35 

comparison of commercial and home- 
made • 20 

comparison of commercial and pepsin. . . .44 
relation to cheese-ripening. 26, 44, 46, 75, 77 
Ripening of cheese (see Cheese-ripening). 

Ripening milk before setting 67 

Room, curing for cheese (see Curing-rooms). 

Rusty spots in cheese 38, 42 

Sage cheese 10 

Salt, effect on action of rennet in cheese-ripening . .40, 44, 46 
effect on action of enzyms in cheese-ripening, 40, 44, 46 

effect on moisture in cheese 46, 66 

effect on quality of cheese 46, 66 

brine, cheese protein soluble in 40, 44-46 

Schools, dairy 54 

Separator, centrifugal, cleaning milk with .......... .24, 66 

removing casein from milk with. . .67 

Skim-milk, effect of use in cheese-making 20-25, 37 

relation of fat to casein in 20-25, 37 

ripening of cheese made from 46 

Solids in cheese 20-35, 67 

in milk 20-35, 67 

in whey 20-35, 67 

Sour milk, making cheese from 73 

Souring of milk, associative action of bacteria in 1 1-14 

Specific gravity, relation of milk-solids to 67 

Spots, rusty, in cheese 38, 42 

Starter, use in cheese-making 20-25, 68 

Statistics of the dairy -^2 

Stirred-curd and cheddar processes, comparison of, 10, 20-25 

Sugar in cheese 20-3 5 , 49 

in milk 20-3 5 

in whey 20-35 

Sweet flavor in cheese ^° 



INDEX TO LITERATURE OF CHEESE-MAKING 47 1 

Swiss cheese, manufacture of 82 

yeast fermentation in 82, 83, 85 

Taints in milk and cheCvSe (see Cheese and milk). 

Temperature in cheese-making 20-35 

in cheese-ripening (see Cheese-ripening). 

Texture of cheese, influence of acid on 67 

relation to conditions of ripening, 
_ 39, 45-46, 55, 58-59, 76-80, 90-92, 102, 105 

Udder, bacteria in and enzyms in milk 4, 40 

Varieties of cheese, descriptions and analyses of 60 

Water in cheese 20-35 

effect on commercial quality, 41, 45-46, 

55, 58-59, 79 

market value of 45-46 

value to consumers and dairymen 46 

in milk 20-35 

in whey 20-35 

Weight lost by cheese in ripening, 41 . 45, 55, 58-59, 66, 69, 

78-79, 90-92, 102, 105 

Whey, albumin in 20-3 5 

analyses of 20-3 5 

butter 2, 132 

casein in 20-3 5 

composition of 20-35 

feeding value of 65 

solids in 20-35 

Wisconsin, cheese industry of 70 

Yeasts in cheese-making, troubles from 82, 83, 85 

Yield of cheese and composition of milk 20-35 



Index 



Page 

Absorption of flavors by milk ... 6 
Absorption of flavors by milk 

from foods 7 

Acid body, cause, prevention, etc. 

of... 122 

Acid calcium phosphate in cheese- 
ripening 358 

Acid flavor in cheese, cause, pre- 
vention, etc 116 

Too little 82 

Too much 82 

Acid, lactic, action in cheese- 
ripening 356 

Fermentation 292 

Abnormal 295 

From milk-sugar 149 

Acid salts, effect on rennet action 308 

In cheese-ripening 334 

Acid test, Mann's 427 

Acid-cut color 89, 129 

Acidity and body of cheese 52 

Color of cheese 52 

Contraction of curd 51 

Expulsion of whey 52 

Finish of cheese 53 

Flavor of cheese 52 

Keeping quality of cheese. ... 53 

Rennet action 51 

Texture of cheese 52 

In cheese, excessive, causes of. 51 

Cheese-making, control of . . . . 53 

In curd and cheese, effects of . . 45 
In curd and cheese, conditions 

of 45 

Insufficient, cause of 50 

Of cheese, excessive, causes of 50 

Of milk...... .. 152 

Of milk in ripening 21 

Of milk, quick test for 428 

Of whey from curd at salting. 37 

Of whey in heating curd 30 

Of whey when cheddaring is 

complete 35 

Of whey when drawn from curd 31 

Of whey, testing 428 

Relation of, to moisture, in curd 47 

Test..... 426 

Test for ripening milk 21 

A-cids, action on casein 143 

Effect on rennet action 306 

In cheese-ripening, action of. . 356 

Use of, in cheese-making 63 



Page 

Aeration of milk 12 

Albumin in milk and cheese-mak- 
ing 139 

Relation to casein 172 

Alkaline salts, effect on rennet 

action 308 

Alkaline tablet test, Farrington's 427 

Alkalis, action on casein 145 

Effect on rennet action 308 

American cheddar cheese, sizes of 44 

Amino acids in cheese 331 

Ammonia in cheese 331 

Appearance of cheese, definition 

t of 90 

Architecture of cheese-factories. . 98 

Ash of milk 150 

Ayrshire milk, composition of 

cheese from 232 

Babcock test for fat in milk 423 

Bacillus lactici acidi 292 

Bacteria, action in cheese-ripening 371 
Action of sunlight, chemicals, 

etc 289 

Ball-shaped 287 

Changes produced by 289 

Corkscrew-shaped 287 

Description of 287 

Digesting 295 

Distribution of 281 

Effect of temperature 288 

Food requirements of 288 

Gas-producing 29? 

Growth and reproduction 287 

Kinds of 287 

Producing bad flavors 296 

Rodyshaped 287 

Bacterial infection of milk, 

sources of 4 

Bitter flavor 83 

Body, acid, cause, remedy, etc. , of 122 

Cause, etc., of defects in 121 

Corky 87 

Crumbly 88 

Curdy 87 

Dry, cause, remedy, etc 121 

Firm 87 

Gritty 88 

Mealy 88 

Meaty 87 

Of cheese and acidity 52 

Of cheese, definition of 86 

Of cheese , effect of moisture on 47 

473 



474 SCIENCE AND PRACTICE OF CHEESE-MAKING 



Page 

Body of cheese, testing 87 

Overdry 88 

Pasty 87 

Perfect 87 

Salvy 87 

Silky 87 

Smooth 87 

Solid 87 

Stiff 87 

Watery 88 

Waxy 87 

Weak 87 

Borax, effect on rennet action. . . 308 

Boxes, cheese, stenciling 77 

Boxing cheese for shipment 77 

Brands on cheese, use of 72 

Breed, influence of, on fat and 

casein 165 

Breeds of cows, casein and albu- 
min in milk of 173 

Brine-soluble protein in cheese- 
ripening 359 

Brine-soluble substance from 

casein 147 

Butter and cheese, making of . . . 69 
Butter-fat (see Milk-fat). 

Butter, whey, inanufacture of . . . 65 
Calcium phosphate, insoluble, in 

cheese-ripening 358 

Soluble in cheese-ripening 358 

Calcium salts, action on para- 
casein 304 

Effect on rennet action 306 

In milk, action of rennet on . . . 304 
Calculating cheese yield, accuracy 

of methods 226 

Cheese yield from fat 213, 224 

Cheese yield from fat and casein 

216, 225 
Cheese yield for different per- 
centages of water 224 

Dividends at cheese-factories. . 279 

MUk-solids 438 

Per cent of casein in milk 170 

Yield of green cheese 211 

Yield of ripe cheese 225 

Care of cheese 71 

Of milk at factory 17 

Of milk at farm 3 

Casein, action of acids on 143 

Action of alkalis on 145 

Action of enzyms on 147 

Action of heat on 146 

Action of rennet on 146 

Action of salts on 146 

Amount of, in milk 161 

And albumin, relations of, in 

milk 172 

And fat, average in factory milk 1 72 
And fat, calculating cheese 

yield from 216, 220 

And fat in milk, relation of . . . . 164 



I»age 

Casein and fat, paying for milk 

on basis of 269 

And fat, relation to cheese yield 187 
And fat, relation of, in factory 

milk 167, 169 

And paracasein, relation of . . . . 305 

And stage of lactation 162 

Brine-soluble substance from. 147 
Calculated, and fat, paying for 

milk on basis of 276 

Calculating amount of, in milk 170 

Change of, into paracasein .... 303 

Composition of 141 

Differing from paracasein .... 303 

Digestion by rennet 306 

Functions of, in cheese 178 

In cheese-factory milk 163 

In milk, effect of drouth on. . . 163 

In milk, effect of pasturage on 163 

In milk, insoluble 142 

In milk of different breeds of 

cows 161 

Loss of, in cheese-making 194 

Test for 439 

Caseoses in cheese 330 

Central curing-station 394 

Cheddar cheese, American, sizes of 44 

Defects in 113 

From pasteurized milk 60 

Cheddaring curd, operations of . . 32 

Cheddaring operation, objects of 34 

Operation, when complete. ... 35 

Texture produced by 35 

Velvety appearance of curd in 35 

Cheese, acid flavor in 116 

Acidity and finish of 53 

Acidity and keeping-quality of 53 

American cheddar, sizes of . . . . 44 

Amino acids in 331 

Ammonia in 331 

And butter, making of 69 

And whey, distribution of milk 

constituents in 203 

Body of, and acidity 52 

Boxing for shipment 77 

Calculating yield of 211 

Care of 71 

Caseoses in 330 

Causes of excessive acidity in. . 50 

Causes of excessive moisture in 46 

Causes of insufficient acidity in 50 

Changes in fat of, in ripening. . 331 

Cheddar, defects in 113 

Club, making of 405 

Commercial qualities of. .... . 80 

Composition, effect of skim- 
ming milk on 234 

Composition of, and milk con- 
stituents 231 

Composition of, and quality. . . 243 

Conditions of acidity of 45 

Conditions of moisture in ... . 45 

Color of, and acidity 52 



INDEX 



475 



Page 
Cheese, cottage, composition of 40^ 

Cottage, making of 400 

Covering with paraffin. ...... 74 

Cracked rinds in 133 

Crean., making of 405 

Defects in flavor of 115 

Definition of body of 86 

Definition of flavor of 84 

Definition of texture of 84 

Drawing to shipping point. ... 78 

Dressing of 43 

Edam, making of 406 

Effect of freezing on cjuality of 390 
Effect of paraffining on loss of 

weight of 319 

Effects and control of moisture 

in. 45 

English sage, making of. .... . 399 

Excessive acidity in, cause of. . 50 

Finish in 91 

Flavor of, and acidity 52 

Flavors, causes of 375 

Food flavors in 119 

From Ayrshire milk, composi- 
tion of 232 

From Guernsey milk, composi- 
tion of 232 

From Holstein milk, composi- 
tion of 232 

From Jersey milk, composition 

of 232 

From normal milk, composition 

of 231 

From pasteurized milk 60 

From rich milk, composition of 237 
From skimmed milk, composi- 
tion of 233 

Functions of casein in 179 

Functions of fat in 177 

Functions of water in 180 

Gas-holes in 86 

Gassy, green fodder a source of 7 

Gouda, making of 415 

Home-trade 62 

How to sell 78 

Immediate removal from fac- 
tory 393 

Judging commercial qualities of 

80, 91 

Mechanical holes in 86 

Methods of grading 95 

Methods of scoring 93 

Milk constituents and yield of 186 
Milk-sugar, changes of, in 

ripening . 333 

Moisture in, effects on weight 

lost in ripening 323 

Moisture in, right amount. . . . 382 

MoLdv, cause, etc 134 

Neuf hatel, making of 404 

Off flavors in 116 

Paranuclein in 330 



Page 

Cheese, paying for 79 

Peptones in 330 

Placing in curing-room 71 

Poison 68 

Profits from proper ripening of 391 
Proteins in, agents changing. . 355 
Quality of, in rel tion to mois- 
ture. . . . 381 

Quick-ripening 60 

Red spots in 89 

Ripe, calculating yield of 22 5 

Sale of 71 

Sampling of 80 

Shipment of 71, 73 

Size of, effect of weight lost in 

ripening 320 

Skim-milk 250 

Slow ripening 60 

Standards of states 241 

Standard of United States. ... 237 

Stilton, making of 398 

Testing 80 

Testing body of 87 

Testing color of 88 

Testing flavor of 81 

Testing texture of 84 

Texture of, and acidity 52 

Texture of, effect on loss of 

moisture 324 

Turning of 72 

Unclean surface of, remedy. . . 133 

Uncolored 89 

Unripe, acid salts in 328 

Unripe, chemical compounds in 32 7 

Unripe, milk-sugar in 328 

Unripe, neutral salts in 328 

Unripe, proteins in 328 

Unripe, salt in 329 

Water in, value to consumers. . 383 
Water in, value to dairymen. . 380 

Weighing for shipment 76 

White specks in 88, 332 

With different percentages of 

water, calculating yield of. . 224 
Yeasty, cause, prevention, etc. 126 
Yield, accuracy of methods of 

calculating 226 

Yield and solids, paying for 

milk on basis of 261 

Yield, calculating from fat, 213, 225 
Yield, calculating from fat and 

casein 216, 220 

Yield, factors of 186 

Yield of, effect of skimming 

milk on 234 

Yield of, effect of starters on. . 69 
Yield, relation of fat and casein 

to 187 

Yield, relation of milk-fat to. . 204 

Yield, relation of water to. . . . 198 

Cheese-box, proper appearance of 78 

Cheese-boxes, stenciling 77 



47^ SCIENCE AND PRACTICE OF CHEESE-MAKING 



Page 

Cheese-brands, use of 72 

Cheese-factories, calculating divi- 
dends at 279 

Paying for milk at 253 

Cheese-factory architecture 98 

Association 449 

Co-operation 448 

Construction 97 

Curing-room in 102, 394 

Drainage 99 

Equipment 106 

Furnishings 106 

Losses in ripening 379 

Management 447 

Method of disinfecting 132 

Milk, casein in 163 

Milk, composition of 175 

Milk, fat in 159 

Milk, relation of fat and casein 169 
Milk, variations in composition 

of 176 

Organization 447 

Plans of construction 105 

Water supply of 99 

Cheese-making and micro-organ- 
isms 285 

Care of milk for 3 

Clean milk for 3 

Colostrum milk in 12 

Control of acidity in 53 

Control of moisture in 48 

First steps in 15 

Functions of casein in 178 

Functions of milk constituents 

in 177 

Functions of milk-sugar in. . . . 182 

Functions of salts of milk in. . 184 

Granular process of 55 

Judging milk for 12 

Loss of casein in 194 

Loss of milk-fat in 188 

Loss of milk constituents in. . . 188 

Paying for milk for 253 

Relation of enzyms to 285 

Ripening milk for 18 

Science of 137 

Soaked-curd process of 57 

Stirred-curd process of 55 

System of records for 16 

Use of acids in 63 

Use of pepsin in 64, 312 

Use of starter in 21 

Oheese-producing solids in milk. . 200 

Cheese-ripening 313, 327, 354, 379 

Acid salts in 334 

Action of acids in 356 

Action of bacteria in 371 

Action of galactase in 368 

Action of pepsin in 365 

Action of rennet on 346, 361 

Causes of chemical changes of, 354 

Chemical changes in 327 



Page 

Cheese-ripening, changes in 314 

Changes in proteins in 330 

Chemical, definition of 337 

Conditions affecting quality 

324, 388 

Cumulative products in 350 

Effect of moisture on chemistry 

of ". 340 

Effect of moisture of air on 

weight lost in 317 

Effect of paraffin coating on 

319, 389 

Effect of salt on 343 

Effect of size 3-42 

Effect of size on weight lost in 

320, 387 
Effect of temperature on loss of 

weight in 315 

Effect of temperature on 

quality 324, 388 

Effect of time on chemical 

changes of 337 

Factory losses in 379 

Gases in 334 

Influence of products on 351 

Loss of weight in 314 

Measuring rate of 336 

Milk-sugar in 357 

Neutral salts in 334 

Proper conditions 394 

Temperature and weight lost. . 386 

Transient products in 350 

Why moisture affects 353 

Cheese-scoring cards 94 

Chemical changes in cheese-ripen- 
ing 327 

Of cheese-ripening, causes of . . 354 
Of cheese-ripening, effect of 

temperature on 338 

Of cheese-ripening, effect of 

time on 337 

Chemical compounds in unripe 

cheese 327 

Chemical products of cheese- 
ripening, effect on process. . 351 
Chloroform, effect on rennet 

action . . -. 308 

Chymosin of rennet 299 

Clean flavor 82 

Milk for cheese-making 3 

Milk, how to obtain 8 

Cleaning and disinfecting, method 

of 132 

Close texture 86 

Coagulating action of rennet, ex- 
planation of 302 

Coagulation by rennet, imperfect, 

causes of 23 

Of milk, effect of temperature 309 

Color, acid-cut, cause, etc 89, 129 

Defects in, cause, etc 129 

High 89 



INDEX 



477 



Page 

Color, light 89 

Mottled, cause, etc 89, 129 

Of cheese and acidity 52 

Of cheese, testing of 88 

Pale, cause, remedy, etc 129 

Perfect 88 

Rusty-spot, cause, etc 131 

Seamy, cause, etc 89, 130 

Straight 88 

Streaked 89 

Translucent 88 

Wavy 89 

Coloring-matter, adding to milk. 22 

Colostrum milk in cheese-making 12 

Commercial qualities of cheese. . . 80 

Score-cards 94 

Starter 19 

Composition of cheese and milk 

constituents 231 

Of cheese and quality 243 

Of cheese, effect of skimming 

milk on 234 

Of cheese-factory milk 175 

Of cheese from Ayrshire milk. . 232 

Of cheese from Guernsey milk 232 

Of cheese from Holstein milk. . 232 

Of cheese from Jersey milk. . . 232 

Of cheese from normal milk. . . 231 

Of cheese from rich milk 237 

Of cheese from skimmed milk. 233 

Of cottage-cheese 404 

Of milk, diagram showing. ... 195 

Of whey 195 

Constituents of milk 139, 

Of milk, conditions affecting. . 155 

Construction of cheese-factory. . . 97 

Of curing-room 102 

Corky body 87 

Cottage-cheese, composition of. . 404 

Making of 400 

Qualities of 403 

Yield of 403 

Cows, fat in milk of breeds 157 

Cowy flavor 83 

Cracked rinds, cause, etc 133 

Cream cheese, making of 405 

Crumbly body 88 

Cubes of curd 26 

Curd, acidity of whey when drawn 

from 31 

Amount of salt to use on 38 

Behavior after cutting 27 

Cheddaring, operations of 32 

Conditions of acidity of. 45 

Conditions of moisture in 45 

Contraction of, and acidity. . . 51 

Cubes of 26 

Effects and control of acidity in 45 
Effects of cutting fine or coarse 27 
Effects of pressing at low tem- 
peratures 41 



Page 

Curd, effects of pressing at high 

temperatures 41 

Film on 29 

Firming of 29 

Heating 29 

How high to heat 29 

How to apply salt to 39 

How to cut 26 

How to press 42 

Length of strings on hot iron, at 

salting 37 

Matting of 32 

Milling objects of 35 

Piling of 32 

Preparation of hoop for 42 

Pressing 40 

Pressing, objects of 41 

Pressing of, regulation of 42 

Purpose of cutting 25 

Regulation of heating 30 

Removal of whey from 31 

Rule for heating 30 

Salting 37 

Salting, effects 39 

Stirring after cutting 28 

Stirring to dry 32 

Stringing of, on hot iron. .31, 35, 37 
Temperature of, at pressing. . . 40 
Texture of, produced by ched- 
daring 35 

Velvety appearance in ched- 
daring 35 

When to cut 25 

When to heat 29 

When to mill '. 35 

When to press 40 

When to remove whey from ... 31 

When to salt 37 

Curd-test, Wisconsin 434 

Curdy body 87 

Curing-room at cheese-factory. . . 394 

Construction of 102 

Effect of moisture in, on weight 

lost 317 

Placing cheese in 71 

Curing-stations, central 394 

Cutting curd fine or coarse, effect 

of 27 

Curd, rules for 25 

Stirring curd after 28 

Daisies, size of 44 

Defects in body, cause, preve.i- 

tion, etc 121 

In cheddar cheese 113 

Color, cause, etc 129 

In finish, cause, etc 129 

In flavor 115 

Digesting action of rennet 306 

Bacteria 295 

Dirt in milk, tests for 433 

Disinfecting, method of 132 

Dissolving action of rennet 306 



478 



SCIENCE AND PRACTICE OF CHEESE-MAKING 



Page 
Dividends, calculation of, at 

cheese-factories 279 

Drainage of cheese-factory 99 

Dressing of cheese 43 

Drouth, effect upon relation of fat 

and casein 168 

Effect on milk-casein 163 

Dry body, cause, remedy, etc., of 121 

Drying curd by stirring 32 

Edam cheese, making of 406 

Educational score-cards 94 

English sage cheese, making of . . 399 

Enzym, pepsin 312 

Rennet, conditions of action. . 306 

Rennet, digesting action of . . . 306 

Enzyms, action on casein 147 

And cheese-making 285, 291 

In milk 297 

Of milk 153 

Equipment of cheese-factory. . . . 106 

Export Cheddar cheese, size of . . . 44 

Factors of cheese yield 186 

Factory architecture 98 

Construction and material for, 97, 98 

Drainage 99 

Equipment 106 

First care of milk at 17 

Location of 97 

Method of disinfecting 132 

Milk, fat and casein in 172 

Plans of construction 105 

Site of 97 

Water-supply of 99 

Farrington's alkaline tablet test. 427 

Fat, amount of, in milk 156 

And calculated casein, paying 

for milk on basis of 276 

And casein average in factory 

milk , 172 

And casein, calculating cheese 

yield from 216, 220 

And casein, effect of drouth 

upon relation of . 168 

And casein in milk, influence of 

breed on 165 

And casein in milk, relation of 164 
And casein, influence of lacta- 
tion on relation of ........ . 166 

And casein, paying for milk on 

basis of 269 

And casein, relation of, in fac- 
tory milk 169 

And casein, relation to cheese 

yield 187 

Calculating cheese yield from 

213, 224 

Functions of, in cheese ....... 177 

In cheese, changes in ripening 331 

In cheese-factory milk 159 

In milk 140 

In milk, Babcock test for 423 

In milk, effect of pasturage on 160 



l^age 
Fat, in milk, influenced by lacta- 
tion 158 

In milk, losses in cheese-making 188 

In milk, relation to cheese yield 204 

In whey 190, 197 

Lost in cheese-making, condi- 
tions favoring 192 

Paying for milk on basis of . . . 258 
Plus 2 method of paying for 

milk 264 

Globules in milk 140 

Fermentation, definition of 285 

Lactic acid 292 

Lactic acid, abnormal 295 

Test . 434 

Ferments, characteristics of 286 

Chemical 286, 291 

Definition of 285 

Organized 286 

Unorganized 286, 291 

Film on curd 29 

Finish and acidity of cheese 53 

Defects in, cause, etc 129 

In cheese 91 

Of cheese, effects of moisture on 48 

Firm body 87 

Firming curd 29 

First steps in cheese-making. ... 15 
Fish-eye texture, cause, remedy, 

etc 126 

Fishy flavor 83 

Flat flavor 82 

Flats, size of . . 44 

Flavor, bitter 83 

Clean 82 

Cowy 83 

Fishy 83 

Flat 82 

Fruity 83, 118 

High 82 

Hydrogen sulphid 83 

Low 82 

Of cheese and acidity 52 

Of cheese, defects in 115 

Of cheese, definition of 84 

Of cheese, effect of moisture on 48 

Of cheese, testing 81 

Perfect 82 

Quick 82 

Rancid S3 

Sour 83 

Stable 83 

Strong 82 

Sweet '83 

Tainted ^3 

Tallowy 83 

Too little acid 82 

Too much acid 82 

Weedy 83 

Flavors, absorption of, by milk . . 6 

Acid, in cheese 116 

Absorption from food by milk 7 



INDEX 



479 



Flavors, bacteria producing bad 296 

Food, in cheese 119 

Fruity, in cheese 118 

Of cheese, causes of 375 

Off, in cheese 116 

Food flavors in cheese, cause, 

remedy 119 

Foods, absorption of flavors from, 

by milk 7 

Formaldehyd, efifect on rennet 

action 308 

Freezing cheese, effect on quality 390 

Fruity flavor 83, 118 

Functions of casein in cheese- 
making 178 

Of milk constituents in cheese- 
making 177 

Of milk-sugar in cheese-making 182 
Of salts of milk in cheese-mak- 
ing..... 184 

Of water in cheese 180 

Galactase 297 

Action in cheese-ripening 368 

And cheese-ripening. 368 

Properties of. .... 298 

Gases in cheese-ripening 334 

Gas-holes in cheese 86 

Gas-producing bacteria 295 

Gassy milk and cheese, green fod- 
der as a source of 7 

Texture, cause, prevention, etc. 124 

Gouda cheese, making of 415 

Grading cheese 95 

Granular process of cheese-mak- 
ing 55 

Greasy texture, cause, prevention, 

etc 125 

Green fodder, source of gassy milk 

and cheese 7 

Gntty body 88 

Guernsey milk, composition of 

cheese from 232 

Heat, action of, on casein 146 

Effect of, on rennet 310 

Heating curd, rule for 30 

Curd, temperature of 29 

Curd, when to begin 29 

High color 89 

Flavor 82 

Holstein milk, composition of 

cheese from 232 

Home-made rennet-extract 300 

Home-trade cheese 44, 62 

Hoop, preparing to receive curd . . 42 
Hot iron, stringing of curd on 

31. 35, 37 

Hot-iron test 438 

Hydrogen-sulphid flavor 83 

Jersey milk, composition of cheese 

from 232 

Judging cheese 80, 91 

Cheese, scale of points for 92 



Page 
Judging cheese, milk for cheese- 
making 12 

Keeping quality of cheese and 

acidity 53 

Of cheese, effect of moisture on 48 
Lactation and casein in milk. ... 162 

Effect on fat in milk 158 

Effect on relation of fat and 

casein 165 

Lactic acid, action in cheese- 
ripening 356 

Fermentation 292 

Fermentation, abnormal 295 

From milk-sugar 149 

Lactometer, Quevenne, use of . . . 437 
Lactose (see Milk-sugar). 

Light color 89 

Location of factory 97 

Longhorn cheese, size of 44 

Loose texture, cause, remedy, etc. 

86. 123 

Loss of casein in cheese-making. . 194 

Of fat, conditions favoring. ... 192 

Of fat in cheese-making 190 

Of moisture, effect of cheese 

texture on 324 

Of weight in cheese-ripening, 
effect of temperature on ... . 315 
Losses of milk constituents in 

cheese-making 188 

Low flavor 82 

Mann's acid ^st 427 

Marschall test for ripening milk 

21, 429 

Matting of curd 32 

Mealy body 88 

Meaty body 87 

Mechanical holes in cheese 86 

Metals, effect on rennet action . . 309 
Micro-organisms, action in cheese- 
ripening 371 

And cheese-making 285 

Milk, absorption of flavors by. . . 6 

Acidity of ........ 152 

Acidity of. in ripening 21 

Addition of rennet-extract to. . 23 
Adding coloring matter to. . . . 22 

Aeration of 12 

Albumin and cheese-making. . 139 

Ash of 150 

Albumin, relation to casein. . . 172 
At cheese" factories, paying for. 253 
Ayrshire, composition of 

cheese from 232 

Baboock test for fat in 423 

Care of, for cheese-making .... 3 
Bacterial infection of, sources. 4 
Cheese-factory, composition of 175 

Cheese-factory, fat in. 159 

Clean, for cheese-making 3 

Clean, how to obtain. . 8 

Colostrum in cheese-making. . . 12 



480 SCIENCE AND PRACTICE OF CHEESE-MAKING 



Page 
Milk, conditions affecting con- 
stituents of 155 

Constituents and cheese yield. 186 
Constituents and composition 

of cheese 231 

Constituents, distribution in 

whey and cheese 203 

Constituents, functions of, in 

cheese-making 177 

Constituents, losses of, in 

cheese-making 188 

Constituents of 139 

Diagram showing composition 

of 195 

Enzyms in. .... : . 153, 297 

Factory, casein in 163 

Factory, relation of fat and 

casein in 169 

Factory, variations in composi- 
tion of 176 

Finding degree of ripeness of . . 21 

First care of, at factory 17 

Freshly drawn, effect of rennet 

on 310 

Gassy, green fodders a source.of 7 
Guernsey, composition of 

cheese from • . •_• 232 

Holstein, composition of cheese 

from 232 

Jersey, composition of cheese 

from 232 

Judging for cheese-making. ... 12 
Normal, composition of cheese 

from 231 

Pasteurized, cheese from ... 60, 404 
Paymg for, on basis of cheese 

yield and solids 261 

Paying for, on basis of fat 258 

Paying for, on basis of fat and 

casein 269 

Paying for, on basis of fat_and 

calculated casein. 276 

Paying for, on basis of "fat 

plus 2" 264 

Paying for, on basis of weight 257 
Relation of casein and albumin 

in .••■.■•• 172 

Relation of fat and casein in. . 164 
Rich, composition of cheese 

from 237 

Ripening for cheese-making. . . 18 

Salts of 150 

Skimmed, cheese from 250 

Skimmed, composition of cheese 

from 233 

Skimming, effect on composi- 
tion and yield of cheese. . . . 234 

Tests for dirt in 433 

Treatment of, after milking. . . 10 

Water in 139 

Whey and cheese-solids in. . . . 201 



Page 

Milk-cans, rusty, effect on rennet 

action 309 

Milk-casein, action of acids on. . . 143 

Action of alkalis on 145 

Action of enzyms on 147 

Action of heat on 146 

Action of rennet on 146 

Action of salts on 146 

Composition of 141 

Effect of drouth on 163 

Effect of pasturage on 163 

In factory milk 163 

Physical condition of 142 

Rule for calculating amount of 170 
Strength of rennet in coagulat- 
ing 302 

Variations 161 

Milk-fat 140 

And breeds of cows 157 

And lactation 158 

Effect of pasturage on 160 

Functions in cheese 177 

In factory milk 159 

In whey 190 

Losses of, in cheese-making. . . 188 
Paying for milk on basis of. . . . 258 

Relation to cheese yield 204 

Variation of 157 

Milks, different, effects of rennet 

on 311 

Milk-pails, sanitary 10 

Milk-solids, calculation of 438 

Milk-sugar 148 

Functions of, in cheese-making 182 

In cheese, changes of 333 

In cheese-ripening 357 

In unripe cheese 328 

Lactic acid from 149 

Milling curd, objects of 35 

Moisture, deficient, in curd, effects 

of 45 

Effect on body of cheese 47 

Effect on chemistry of cheese- 
ripening 340 

Effect on finish 47 

Effect of, on flavor of cheese ... 48 
Effect on keeping quality of 

cheese 48 

Effect on texture of cheese. ... 47 
Excessive, in curd, effects of . . 46 
How much cheese should have 382 
In cheese, affecting quality. ... 381 
In cheese, effect on weight lost 

in ripening • • • 323 

In cheese-making, control of . . 48 
In curd and cheese, effects of . . 43 
In cheese, effect of texture on 

loss of 324 

Of air, effect on weight lost m 

ripening 317 

Relation of, to acidity in curd. 4) 



INDEX 



481 



Page 
Moisture, variation in. loss with 

different kinds of cheese. ... 321 
Why it affects ripening of 

cheese 353 

Moldy cheese, cause, etc 134 

Monrad test for ripening milk. .21, 431 

Mottled color 89, 129 

Natural starter 18 

Neufchatel cheese from pasteur- 
ized milk, making of 404 

Neutral salts in cheese- ripening. 334 
Off flavors in cheese, cause, rem- 
edy, etc 116 

Open texture, cause, prevention. 123 

Overdry body 88 

Package, cheese 91 

Pale color, cause, remedy, etc. . . 129 
Paracasein, action of calcium salts 

on 304 

And casein, relation of 305 

Change of casein into 303 

Digestion by rennet 306 

Distinction from casein 303 

Precipitation by calcium salts. 304 
Paraffin coating on cheese, effect 

on quality 389 

Covering cheese with 74, 387 

Paraffining cheese, effect on 

weight lost in ripening 319 

Paranuclein in cheese 330 

Pasteurized milk, cheese from. . . 60 
Pasturage, effect on casein in milk 163 

Pasty body 87 

Patrons' statement 447 

Paying for milk at cheese-factories 253 
On basis of cheese yield and 

solids 261 

On basis of fat 258 

On basis of fat and calculated 

casein 276 

On basis of fat and casein 269 

On basis of "fat plus 2" method 264 

On basis of weight ....._. 257 

Pepsin, commercial, action in 

cheese-ripening 365 

Enzym 312 

Method of testing 433 

Use in cheese-making 64, 312 

Peptones in cheese 330 

Perfect body 87 

Color 88 

Flavor 82 

Texture 85 

Picnic cheese, size of 44 

Piling of cvird 32 

Pin-hole texture 86 

Plans of factory construction. . . . 105 

Poison in cheese 68 

Porous texture 86 

Pressing curd 40 

At high temperatures, effects of 41 
At low temperatures, effects of 41 



Page 

Pressing curd, conditions of 40 

How regulated 42 

Objects of 41 

Temperature of curd at 40 

Print cheese, size of 44 

Profits from proper ripening of 

cheese 391 

Propagation of starter 20 

Protein, brine-soluble, in cheese- 
ripening 359 

Proteins, changes in cheese-ripen- 
ing 330 

In cheese, agents changing. ... 355 

In unripe cheese 328 

Qualities, commercial, of cheese . . 80 
Quality of cheese and composition 243 

Affected by moisture 381 

Effect of freezing on 390 

Effect of paraffin coating 389 

Effect of temperature on 388 

Quevenne lactometer, use of . . . . 437 

Quick flavor 82 

Quick-ripening cheese 60 

Rancid flavor 83 

Records, system of, for cheese- 
making 16 

Red spots in cheese 89 

Rennet action and acidity 51 

Effect of acid salts on 308 

Effect of acids on 306 

Effect of alkaline salts on 308 

Effect of alkalis on 308 

Effect of borax on 308 

Effect of calcium salts on 306 

Effect of chloroform on 308 

Effect of formalin on 308 

Effect of metals on 309 

Effect of rusty milk-cans on . . . 309 

Effect of salt on 308 

Effect of temperature on 309 

In cheese-ripening 361 

On calcium salts of milk 304 

On casein 146 

On different milks 311 

Rennet coagulation, effect of 

water on 307 

Explanation of 302 

Imperfect, causes of 23 

Rennet, effect of heat on 310 

Effect of sunlight on. 310 

Effect on cheese-ripening 346 

Effect on freshly drawn milk. . 310 

Source of 300 

Strength of, in coagulating milk 302 

Test, Marschall 429 

Test, Monrad 431 

Rennct-enzym, conditions of 

action 306 

Dissolving action of 306 

Rennet-extract, addition of, to 

milk 23 

Amount to use 22 



482 SCIENCE AND PRACTICE OF CHEESE-MAKING 



Page 
Rennet-extract, commercial .... 301 

How made 300 

Method of testing 432 

Rennin of rennet. . 299 

Rich milk, composition of cheese 

from 237 

Rinds, cracked, cause, etc 133 

Ripe milk, acidity of 21 

Ripeness of milk, finding degrees 

of 21 

Ripening milk for cheese-making 18 

Milk, objects of 18 

Of cheese 313 

Of cheese, acid salts in 334 

Of cheese, changes in 314 

Of cheese, changes in proteins 

in . 330 

Of cheese, chemical changes in 327 
Of cheese, efifect of temperature 

on weight lost in 315 

Of cheese, measuring rate of . . 336 

Of cheese, neutral salts in 334 

Of cheese, profits from proper. 391 
Rule for calculating casein in milk 1 70 
Rusty milk-cans, effect on rennet 

action 309 

Rusty spots, cause, etc 131 

Sale of cheese 71 

Salt, amount to use on curd 38 

Effect on cheese-ripening 343 

Effect on rennet action 308 

How to apply to curd 39 

In cheese 89 

In cheese, testing 90 

In unripe cheese 329 

When to put on curd 37 

Salting curd, effects of 39 

Curd 37 

Salts, acid, in unripe cheese 328 

Action of, oh casein 146 

Neutral, in unripe cheese 328 

Of milk 150 

Of milk, functions of, in cheese- 
making 184 

Salvy body 87 

Sampling cheese 80 

Sanitary milking-pails 10 

Scale of points for judging 92 

Science of cheese-making 137 

Score-cards, commercial 94 

Educational 94 

Scoring cheese, method of 93 

Seamy color 89, 130 

Septic-tank drainage 100 

Shape of cheese, effect of weight 

lost in ripening 320 

Shipment, boxing cheese for. ... 77 

Of cheese 71 

Weighing cheese for 76 

Shipping cheese 73 

Silky body 87 

Site of factory 97 



Page 

Size and loss of weight 387 

Size of cheese, effect on weight 

lost in ripening 320 

Skim-milk cheese 250 

Skimming milk, effect of, on com- 
position of cheese 234 

Effect on yield of cheese 234 

Skimmed milk, composition of 

cheese from 233 

Slow-ripening cheese 60 

Smooth body 87 

Soaked-curd process of cheese- 
making 57 

Solid body 87 

Solids, cheese-producing, in dif- 
ferent milks 200 

Solids, not fat in milk, calculation 

of 438 

Sour flavor 83 

Specks, white, in cheese-ripening 332 

Square cheese, size of 44 

Stable flavor 83 

Standard for cheese. United 

States 237 

Standards of states for cheese. . . 241 

Starter, commercial 19 

Effect on yield of cheese 69 

Natural.. 18 

Preparation of 18 

Propagation of 20 

Use of, in cheese-making 21 

Stenciling cheese-boxes 77 

Stiff body 87 

Stilton cheese, making of 398 

Stinkers, cause, prevention 116 

Stirred-curd process of cheese- 
making 55 

Stirring curd after cutting 28 

Stirring curd to dry it 32 

Straight color 88 

Streaked color 89 

Stringing of curd on hot iron, 31, 35, 37 
Strings of curd on hot-iron in 

cheddaring 35 

Length of, at salting 37 

Strong flavor. 82 

Sugar in cheese-ripening 357 

In milk 148 

Milk, in unripe cheese. ....... 328 

Sunlight, effect on rennet 310 

Supplies for cheese-factory 106 

Sweet flavor 83 

Swiss-hole texture 86 

Tainted flavor 83 

Tallowy flavor •.••••.• ^^ 

Temperature and loss of weight in 

cheese-ripening 315 

Effect on rennet action 309 

Effect of, on chemical changes 

in cheese-ripening. ........ 338 

Influence on loss of weight in 

ripening 386 



INDEX 



483 



Page 

Temperature of curd at pressing. 40 

Of heating curd 29 

Of ripening, efifect on riuality. . 388 

Test for acidity of milk, whey, etc. 426 

For casein 439 

For dirt in milk 433 

Hot-iron 438 

For acidity for ripening milk. . 21 

Testing acidity of whey 428 

Body of cheese 87 

Cheese 80 

Cheese for salt 89 

Flavor of cheese 81 

Methods of 423 

Pepsin, method of 433 

Rennet-extract, method of. . . . 432 

Texture, cause, etc., of defects in 121 

Close 86 

Defects in, cause, prevention, 

etc 121 

Fish-eye, cause, prevention, etc. 126 

Gassy, cau.se, prevention, etc.. 124 

Greasy, cause, prevention, etc. 125 

Loose 86, 123 

Mechanical holes 86 

Of cheese and acidity 52 

Of cheese, definition of 84 

Of cheese, effect of moisture on 47 
Of cheese, effect on loss of 

moisture 324 

Of cheese, testing 84 

Of curd in cheddaring 34 

Open, cause, prevention, etc.. . 123 

Perfect 85 

Pin-hole 86 

Porous 86 

Swiss-hole 86 

Translucent color 88 

Turning cheese 72 

Twins, Cheddar, size of 40 

Unclean surface, cause, etc 133 

Uncolored cheese 89 

United States cheese standard. . . 237 
Water, calculating cheese j'ield 

for different percentages of. . 224 

Effect on rennet action 307 

Functions of, in cheese 180 

In cheese, value to consumers. 383 

In cheese, value to dairymen. . 380 

In milk 139 

Relation of, to cheese yield. . . . 198 

Water-svxpply of factory 99 

Watery body 88 

Wav, color 89 

Waxy body 87 

WeaK body 87 

Weedy flavor 83 

Weighing cheese for shipment. . . 76 

Weight, loss in cheese-ripening. . 314 



Page 

Weight, lost in cheese-ripening, 

effect of moisture of air on 317 
Lost by paraffined cheese. .319, 387 
Lost in ripening, effect of mois- 
ture in cheese on 323 

Lost in ripening, effect of size 

of cheese on 320, 387 

Lost in cheese-ripening, effect 

of temperature on 315 

Lost in ripening at factories. . . 380 
Lost in ripening, influence of 

temperature on 386 

Lost in ripening, reduction of. 383 

Paying for milk by 257 

Whey, acidity of, at salting curd 37 
Acidity of, in heating curd .... 30 
Acidity of, when drawn from 

curd 31 

And cheese, distribution of milk 

constituents in 203 

Composition of 195 

Distribution and value of 66 

Expulsion of, and acidity 52 

Fat in 190 

Removal of, from curd 31 

Testing acidity of 428 

Variations of constituents 197 

When to remove from curd. . . 31 
Whey-butter, manufacture of. . . 65 
Whey-solids in different milks. . . 201 

White specks in cheese 88, 332 

Wisconsin curd-test 434 

Yeasts 296 

Yeasty cheese, cause, prevention, 

etc 126 

Yield of cheese, accuracy of 

methods of calculating 226 

Of cheese and milk constituents 186 
Of cheese, calculating from fat 

213, 224 
Of cheese, calculating fn^m fat 

and casein 216, 220 

Of cheese, effect of skimming 

milk on v 234 

Of cheese, effect of starters on 69 

Of cheese, factors of 186 

Of cheese, methods of calculat- 
ing 211 

Of cheese, relation of fat and 

casein to 187 

Of cheese, relation of milk-fat 

to 204 

Of cheese, relation of water to 198 
Of cheese with different per- 
centages of water, calculation 

of 224 

Of cottage-cheese 403 

Of ripe cheese, calculation of . . 225 
Young American cheddars, size of 44 



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Soil Physics Laboratory Guide 

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Bean Culture 

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The Potato 

By Samuel Fraser. This book is destined to rank as a 
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Dwarf Fruit Trees 

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Farmer's Cyclopedia 
of Agriculture ^ }» 

A Compendium of Agricultural Scie?ice and Practice 
on Farm, Orchard and Garden Crops, and the 
Feeding and Diseases of Farm Animals • .* • .* 

^y EARLEY VERNON WILCOX, Ph.D 
and CLARENCE BEAMAN SMITH, M.S 

Associate Editors in the Office of Experiment Stations, United States 
Department of Agriculttire 



THIS is a new, practical, and complete pres- 
entation of the whole subject of agricul- 
ture in its broadest sense. It is designed 
for the use of agriculturists who de- 
sire up-to-date, reliable information on 
all matters pertaining to crops and stock, but 
more particularly for the actual farmer. The 
volume contains 

Detailed directions for the culture of every 
important field, orchard, and g'ar den crop 

grown in America, together with descriptions of 
their chief insect pests and fungous diseases, and 
remedies for their control. It contains an ac- 
count of modern methods in feeding and handling 
all farm stock, including poultry. The diseases 
which affect different farm animals and poultry 
are described, and the most recent remedies sug- 
gested for controlling them. 

Every bit of this vast mass of new and useful 
information is authoritative, practical, and easily 
found, and no effort has been spared to include 
all desirable details. There are between 6,000 
and 7,000 topics covered in these references, and 
it contains 700 royal 8vo pages and nearly 500 
suberb half-tone and other original illustrations, 
making the most perfect Cyclopedia of Agricul- 
ture ever attempted. 

Handjomely bound in cloih, <^3.30; half mc 'occo 
{t)ery .tumpluouj), ^4-. 50, postpaid 

ORANGE JUDD COMPANY, "''iUJrB'u&Kt "''• 



